Problem with establishing a garden patch of the parasol mushroom (Macrolepiota procera)

The parasol mushroom (Macrolepiota procera) is native to my land so I have figured out it will be easy to establish a patch of these in my garden. I have prepared a bed with layers of wet corrugated cardboard, and I have used both spore prints and stem butts with some mycelium between the layers. I have covered this with a layer of wood chips and some cloth on top. I have moistened it when there was a dry spell, so I'm pretty sure it has never dried out. It was never too wet as well, since my soil is very sandy and has a very good drainage. After half a year I do not see any sign of mycelium in this bad. What I'm doing wrong?

Do you have any update on this? How has this developed in the meantime?

Oh yes, I do have an update :)

I harvest parasol mushrooms on regular basis in season now, but what they have done is that they have colonized other parts of my garden, rather than stay where I planned them to grow. No complaints about that at all.

ooh! Oh this is an interesting idea, parasols grow around here on the roadsides and I have the same open grassy land but I never thought of trying to "transplant" any. I will try to remember next autumn when they are up again. It would be great to get some more edible mushrooms growing here.

@Skandi Rogers, I should proably add to that, that even bigger success was introduction of Stropharia rugosoannulata - known as  wine cap stropharia, "garden giant", burgundy mushroom or king stropharia. I have innoculated wood chips that went into the paths between my raised beds.



Now these mushrooms grow in numbers exactly where the wooden edge of raised bed meets the path. Everywhere around is a dry sand, so these are not spreading so far.

Well it's not a parasol mushroom I'm starting with although there was a really nice parasol mushroom growing in the same spot it was the other side of the fence and I didn't want to hop over and pinch it. But I do have a huge and very ripe Horse mushroom Agaricus arvensis  that I want to try to "seed", they like growing on pasture, often on rather overgrown pasture which is where I found this specimen. I'm going to have a go at spreading it about my orchard and see if it will take there. I'm not sure if it will be best just to tear it up and drop bits all over or if I should try to be fancier like you were.