Originally Posted by JacobianMatrix
Precisely how many species of mushroom are edible (disregarding the hallucinogenic ones)?
The edibility of many mushrooms is unknown. Despite our best scientific efforts, the only truly reliable way to determine edibility is by eating them. In general, edibility is only known in the cases of mushrooms that are either rather large or very abundant. There are also a good deal of mushrooms that can have variable edibility based on the individual- either mushroom or consumer.
I really only know California mushrooms, which essentially means mushrooms from the west coast of the US. Many of these are the same mushrooms found in other parts of the world, but they will often have different localized forms which may vary in edibility. If I had to give a very rough estimate, there are probably 100-150 types of mushrooms in California that are both edible and worth eating.
It would be much easier to list the poisonous mushrooms. In California, there are only three known mushrooms that are deadly poisonous at moderate levels of consumption. These are Galerina autumnalis, Amanita ocreata, and Amanita phalloides. The Amanitas are described below, and the deadly Galerina is a small brown mushroom usually eaten only by children or people confusing it with hallucinogenic mushrooms. There would be no food value in a mushroom of this size, so I won't go into detail on it.
The number one rule of mushrooms is that you don't eat them unless you are POSITIVE with your identification. As the saying goes, "when in doubt, throw it out."