Here in Maine we have a variety of trees that love wet feet. The red maple for instance, while not a food tree per se, it has a lot of value and LOVES wetland and is often called Swamp Maple for this reason. It is a very hardy tree and has a lot of value commercially and for the homesteader. It is a medium growing tree. It can be tapped like a rock maple though and maple syrup derived from it. It has a more rugged taste, and you don't get as much syrup per tree as a rock maple (also known as sugar or hard Maple), but its still good. It is called Red Maple, Soft Maple, and Swamp Maple too by the way.
Another is the lowly alder. It is a very short tree that seldom gets above 20 feet high or a few inches in diameter, but has uses too. Called "biscuit wood", by the old duffers, back when
wood burning cook stoves was all there was, fires stoked from this wood was hot and fast. Today it would be perfect for
firewood for rocket stoves. It has no commercial value...NONE...but because it loves to be in wet...and I mean saturated open
water type soil...it can be bent into a pretzel and a lot of furnishings can be made from it without sawing or otherwise working it up. It is super fast growing, a sort of willow.
Another is cedar, and while it has some limited commercial use, on a homestead posts destined to be in the ground do well, or as siding. It has no strength for building per se...it cannot handle any sort of shock load, but it will remain rot free for many years. Cedar shingles I nailed onto my Grandmothers house are still solid 30 years later!
Hackmatack, also called Juniper or Larch does well in wet soil. It burns incredibly hot; so hot it will warp a
cast iron woodstove, BUT is like cedar in that it never rots. It is often used for pilings for docks in seaports. It grows incredible fast! Its bark can be used for dyes and tanning. The Eastern Hemlock is very similar to hack, and is a close cousin to say the least. It loves wet feet and can tan and dye things. In fact it was once prized for only its bark! I could be mistaken on this, but I think it can make a type of
root beer too.
Willow is another tree that has no commercial value, but may be of use to a homesteader. The best thing is its ease of transplanting. Cut off a twig, stick it in water over the winter, then plant in a wet spot in the spring. It will take root and grow...really fast. My parents did this when I was born and the tree 42 years later is 16 inches in diameter and 60 feet high. It has uses from furnishing making from its pliable branches, to firewood, to lumber. Unfortunately when I did wrong, I learned its pliable branches could be applied to my backside!!
Yellow Birch loves wet areas. I have seen some where their
roots grew up like stilts on a Louisianan Bayou home, like the roots of a Cypress. It gives a neat wintergreen taste, and can actually be tapped like a Sugar Maple, but no boiling required. And when the sap runs...it gushes out!! It makes a nice sweet wintergreen tasting drink or type of flavoring. (White birch does as well, though it prefers dry feet and is outside the realm of this
thread though).
Brown
Ash is another swamp tree, in fact I have never seen in grow anywhere but in a swamp. It has no food properties, but for a homesteader can make a lot of wooden things, like pack baskets, snowshoes, and sleds. It is really pliable and is conducive to steam bending!
There are many more, but I will end with black spruce. It can withstand standing water it is so hardy. It grows incredibly slow, but I am not sure you can kill it. It has the basic structure of other spruce, so it has great strength to weight ratios and can be sawn into framing lumber commercially. I planted a stand of this in some wetland some 20 years ago and it is absolutely thriving! I won't be able to harvest it in my lifetime (I am 42 years old), but my kids will. It is however a food tree in that it makes a really good beer.
Now not a tree, i do have a naturally occurring cranberry bog, and as a kid used to get cranberries from it with my Grandmother. However we once saw a snake, and seeing as how I dislike them, I have never been back. Now that was 30 years ago so the snake is probably gone, but I am not about to take that chance. But they grow in wet areas and are a nutritious food.