No general, reliable rules exist to identify poisonous mushrooms. Some of the edible varieties are quite easily recognized, but some edible varieties closely resemble poisonous mushrooms and can only be distinguished by an expert. The common lore that poisonous mushrooms make silver spoons turn black while mushrooms that can be peeled are edible is not true. Some of the deadliest mushrooms, amanitas, do not turn silver spoons black and can be peeled! The only rule to follow is that one must be able to identify a mushroom with certainty prior to eating it.