2) Royal Toadstool - Amanita muscaria dont grow in swamps and it is a symbiont with pine and birch. It also has some hallucinogenic effect and probably was a part of a berserker potion.
3) I feel strange finding bloated boletes, bay boletes and morels in fields. They have symbiosis with specific trees and usually grow in woods or only under trees.
4) Add more different mushrooms: oyster mushrooms growing on trees, birch boletes, king boletes, boletus satanas (could be a part of some evil potion), lactaris indigo, bleeding mushroom (Hydnellum peckii), some hallucinogenic mushrooms etc.
