Coprinus comatus (Shaggy Mane)
Cornell University, Ithaca, NY
This is supposed to be pretty tasty when they're really fresh. Luckily you usually won't have to worry about picking an old one. This is a member of the Inky Cap family Coprinaceae. When the mushroom grows old it begins to deliquesce and turn into nothing. These are also important in the medical field; some species in this family contain a toxin that is the active ingredient in Antibuse. So if you do decide to eat one, don't drink or you'll violently sick for a long long time.
