Dietary sources of vitamin D for temperate regions?

Is anyone growing/producing anything with high vitamin D content, or know of good sources, especially for those of us beyond the 35th parallel, where we don't get enough sun 3/4ths of the year?
I was looking at how much food we can produce ourselves on our farm and where our deficiencies lie, and this is a big gap for us. I don't imagine being totally self-sufficient even during these times, but it is now a bit more than just a thought experiment and I would like to shore up our food production and supply as much as I can.

I assume truly free range egg yolks might be at least marginally higher in nutrient value than normal egg yolks but that's about the only good source I know of that I can generate on our farm - luckily for us this one is already present and accounted for and we have enough eggs to share with family and friends. But eggs aren't really sufficient on their own, at least without driving a person mad. Beef cattle are a bit outside the scope of our system (any many permie systems, I would wager). A lot of people rely on (fortified) cereals, juices, milk... cheese, tuna... about the only thing that *grows* that I can find on the lists of recommend dietary sources is mushrooms - I'm curious which ones might be best for vitamin D content and which might be friendliest for beginners?

I must be missing some sources and I'm sure that others here at Permies know of some more underrepresented sources. I'd love to hear your knowledge & experience with mushrooms, or whatever else might be a good source of vitamin D.

I do not think there are any plants that produce vit D. Mushrooms only contain any Vit D if they are grown in light and you need more of it as it's vitamin D2 not D3 which is the one we can utilise best.  Commercial eggs are only 5% each egg double that maybe for a nice sun exposed well fed chicken, I totally agree 10 eggs is a little over the top.

Traditionally it would have come from Fish up here, oily fish have good levels of D but even then that would only have made 20% of so of the US rda. It is a vitamin your body can store (I believe) I personally do not make much if any D from sunlight I had a blood test in August after a sunny summer working in the fields and was only running at 1/3 of the necessary level in my blood. Which means I have to take a supplement as I simply cannot eat enough from food even if I lived on a diet of salmon mushrooms eggs and beef liver.. doesn't sound too bad to be honest.

Mushrooms will create vitamin D if placed in light for a couple hours right before eating them, even store bought buttons.  

In the book 'nourishing fats', tests were done comparing the vitamin D content of pasture-raised animal fat and factory famed animal fat. Pasture-raised animal fat contained many times more vitamin D than indoors animals.

Lard from outdoors-raised pigs is one of the best sources of vitamin D there is, and pigs are great homestead animals, and don't need much land. Some of the pig breeds make more fat than others, so it's worth tracking down a fat breed if you want the lard.

Dairy from outdoors-raised animals has lots of vitamin D as well. If you don't have much land, goats can be kept in a strawyard and have their food brought to them.

Raw extra virgin cod liver oil is a very dense source of vitamin D.

R Scott wrote:Mushrooms will create vitamin D if placed in light for a couple hours right before eating them, even store bought buttons.  

Indeed, I have read the same thing. I've also read it's good to place the mushrooms gill-side toward the sun although even sliced mushrooms put in the sun will work. Below is a link talking about mushrooms and Vitamin D from fungi perfecti (Paul Stamets' site):
https://fungi.com/blogs/articles/place-mushrooms-in-sunlight-to-get-your-vitamin-d

A way to generate and store the vitamin D from mushrooms for winter is to collect or buy mushrooms in summer, and dry them in direct sunlight.

I find that dried mushrooms are a great thing in the winter kitchen. They rehydrate along with other things cooking, such as pasta or meat, and they have a delicious intense mushroom flavor.

UV exposed mealworms have a vitamin D content similar to salmon by weight.  Not the most appetizing of foods, but easy to manage.

There's a lot of good information here, thank you all.

Skandi, I've struggled to get enough vitamin D, I've only been tested in the winter but was quite low and definitely feeling some of the effects. I do take supplements, and try to be mindful of getting enough sun, but I don't want to rely on only those, especially right now. Our stores here are still selling out of about half of the brands of daily vitamins along with cold medicines, etc. I could definitely eat more of most of the things listed in this thread happily, and more varied sources is always a good thing in my book! And I do believe it is stored in body fat, for four weeks or more, at least from my reading.

Kate, we can get pasture-raised animal products locally and try to do so whenever we can, so that's something. I do wish that we could utilize some of our space here for goats of our own, but right now it's not feasible. For those that can work animals into their system, it's definitely a great option. We do plan to get goats within the next 2-3 years once we can build a shed for them and invest in fencing! But fences are a whole other topic....

Mushrooms will create vitamin D if placed in light for a couple hours right before eating them, even store bought buttons.  

Putting mushrooms in sunlight to up their vitamin D content after harvest isn't something I had heard of before, but it makes total sense. That's awesome to know, we've wanted to grow mushrooms for other reasons but that pretty much seals the deal. In the past I've foraged a good supply each late autumn and stored them using a dehydrator, so it sounds like I've been missing out a bit! I love mushrooms for cooking, I'll have to try sun-drying some this spring/summer. Even if it isn't the most useful form of vitamin D, it's something, and mushrooms are great for so many other reasons. Fresh and dehydrated are definitely a staple in Italian cooking which is a mainstay for us. (And now I'm hungry.)

Annie, thanks for the tip about facing them gill-side up. That link is really good reading, too!

UV exposed mealworms have a vitamin D content similar to salmon by weight.

That is awesome to know, thank you! This is the reason I asked here on Permies, because that's exactly the sort of entry missing from lists on more traditional food blogs, etc.
I'm not sure I could eat them myself, much less sell others on the idea, but it's really not that outlandish. I've worked at a shop that sold candied and seasoned insects as a kind of gag gift like these. Looking at those flavor profiles on their site brings some possibilities to mind, anyway. Anybody up for BBQ?

Fatty fish and beef liver...

Probably the best way is ultraviolet light but for people like me up at 47.8 degrees North latitude that may not be a realistic source of Vitamin D for close to half of each year. My last blood test a month ago had me at nearly "low" levels and I drink a good gallon of Vitamin D fortified milk a week.  I also spend around 50 to 60 hours outdoors a week with my arms open to the light, my face, neck and arms are already pretty well tanned this year and we still have snow on the ground at the moment.

In a survivalist situation I would say go for fatty fish like salmon up in this region, or smelt on the west coast.

In a modern life solution I might suggest an ultraviolet bulb or two in the house, two of our six children were born with high bilirubin counts and had to stay under ultraviolet light for 1 to 3 days to get the bilirubin count down.  Both of those children were born in April so most of the pregnancy was during the wintry months here.  Not only can ultraviolet lights improve vitamin D they also help to disinfect, during this current time period that could also be of potential benefit.

Rather than look for a natural approach, a more technical modern medicine approach may be the simplest cheapest and most effective answer.

P.S...   I also meant to mention Black Bullhead catfish are also considered a fatty fish, they have about 14 micro grams of Vitamin D per 100 gram serving, I have four ponds full of these here on the farm.  Having a pond with them could also be a reasonable source, though unlike me you would fish them up and freeze them for winter consumption for winter vitamin D.  I only fish in the late spring, summer and fall here.