My grandad used to go out with a field guide of mushroom species, and pick all those which appeared to be edible. He then vetted them again at home, and binned any suspect dodgy ones. He would then cook up the good ones and keep a little bit in the fridge incase he started to feel ill, so he had something to give to the hospital should the need arise (which it didn't).
Crazy bloke he was.
Crazy bloke he was.