Somebody googled “how to draw mushrooms,” and landed here. Sure, I can put a gnome hat on a tree trunk and call it a fruiting body of a fungus, but you’d be better off looking for the most famous mushroom artist in history. She was an esteemed mycologist back around the turn of the last century, and was particularly respected for her scientific illustrations, which were wide ranging and detailed– this at a time when photography couldn’t provide a natural scientist the color and magnification needed for good texts. She did hundreds of them, as well as publishing scientific papers through her uncle, since they wouldn’t publish articles by a woman who wasn’t even properly trained. In any case, you should probably start there.
I understand she also drew rabbits.