Note: by the "common toadstool," I mean the flat, woody, large roundish ones that grow out of tree trunks. Hope this helps. Sorry I don't know their exact name.

There is there is no 'common toadstool'. There are thousands of species of fungi, hundreds of which grow from trees and none of which should ever be eaten unless identified with 100% certainty by an expert who can see the specimen.

I think caution is best, too. I stick with only those I know well. (About 5 that grow from wood and 3 from the ground.) I avoid any umbrella shaped ones from the ground. Too risky. I'll have to find my guide to fungi in Minnesota and see if I can find the most common toadstool around here that grows shelf-like out from tree trunks, or otherwise consult a specialist. I spoke with the author some years ago, a Professor of Mycology, and he said that all fungi that grow from old or new wood are not toxic with the exception of one that is easily identified. It is bright orange, glows in the dark, has stems in bunches with a round bulb top. Will post a list once I do my research. Thanks to all.

Did some research on the web. It is known as a conk fungus of the polypore group. Maybe also artist's fungus. While not particularly toxic, its tea is used in herbal medicine for its antibacterial properties. It might negatively react with other medications. I'm staying away from it for food and will admire its beauty instead.

PS: "Toadstools" is a misnomer we used as kids.