Just had to register to say troll or not this is the funniest thread I've ever read! If you're serious then don't take people's advice too hard, they just don't want to see you fried or suffocated or your parents busted or house burned down! Sorry dude but if your parents know about your dank cave then I'd love to see this conversation:
*parent looking out whistfully onto the garden, at 30 sq. ft of freshly turned dirt*
"how could you have come up with such a ridiculous idea? You're supposed to be working hard at school!"
"yeah I know I'm sorry it was stupid of me I shouldn't have betrayed your trust"
"..."
"... But erm, since it's there I was thinking we should at least put it to use growing some edible mushrooms, perfect conditions! Maybe some shiitake? I'll help out, won't be any effort!
"
....
" do you seriously think I was born yesterday?"
Anyway man I think the best use of the hole would be to sit outside for a couple hours a day staring at it and contemplating why it was a bad idea and why in the future you should think things through
Not having a go if you actually did this mate cos its lot of work and shows initiative was just a bit misguided is all