Much room for mushrooms?

I asked Small Boy what he wanted to grow, and without any hesitation he said 'mushrooms'.
Now, he doesn't like mush rooms and won't so much as look at one, so I think he said it because he thought it would be a challenge for me, much in the same way as if he had asked me to grow the moon or a cow. However, I like to be challenged and said 'ok then' which is not what his 4 year old mind was expecting.

So, we have mushroom spawn, and we are just preparing our compost. this entails a big tray piled with straw and chicken dung, watered, turned and left to get hot. When it eventually goes all composty, I will spread it in some deep plastic drawers, propagate the spawn, wait to see it on the surface, case it, and wait for button mushrooms. or, something like that.

I have grown them once before from a kit, and they were lovely. I am, however, deeply phobic of polystyrene, so couldn't manage that this time.

We will see. Something new to try, and if they are as nice as last time then it will be worth it.