Yep, that's what my parents taught me. They taught me which mushrooms are absolutely not edible and then few of which are excellent.
But in fact there is one mushroom that is deadly, and forbidden in many countries, but in the nordic countries, especially in Finland, it is eaten as a culinary delicacy. And that one is the one called "korvasieni" (Gyromitra esculenta, eng."false morel"). It contains gyromithrin, which is a lethal and carcinogenic toxin.
Even while most of the poison can be removed by the process of repeated boiling, there will still be minute amounts of the toxin left when it gets on the plate. And because gyromithrin is a cumulative toxin, it is adviced that people do not consume them regularly.
It's a spring mushroom, and while I did find them this year, it was a bit too late in spring, and they were situated in a polluted place so I couldn't pick them for a stew this time.
It's a delicious mushroom though.
I wonder if I can find them next year.
These mushrooms looked very aggressive! I wouldn’t want to eat them; my aggressiveness level is a bit above average!! LoL