Almost every year, someone in California dies from eating the wrong mushroom. There are old mushroom hunters and bold mushroom hunters. But there are no old, bold mushroom hunters. There are no non-scientific tests or rules that can accurately determine the safety or toxicity of a mushroom. Some mushrooms are only poisonous if eaten in large quantities.
Some mushrooms are poisonous when raw but become harmless when parboiled and thoroughly cooked.
Some mushrooms are poisonous regardless of how they are cooked or prepared. Some mushrooms are poisonous only if eaten with alcoholic beverages. Some mushrooms are classified as poisonous because they are hallucinogenic. Some mushrooms that are edible when fresh and young become poisonous when they are old, hit by frost or if they decay. Some mushrooms, for unknown reasons, are poisonous in one part of the country and are not poisonous in another.