Mushrooms are the fleshy, umbrella-shaped sporophores, or fruiting bodies, of many types of fungi. Of little nutritional value, edible mushrooms are usually appreciated for their subtle flavor and unusual texture.

Several varieties of fungus are associated with mushrooms, although many of them are not safe to eat. In fact, poisoning by wild mushrooms is a fairly common occurrence and can be fatal. Thus, it is extremely important that all mushrooms that are to be eaten are first clearly identified. Some prominent cases of mushroom poisoning, however, may have been intentional. The Roman emperor Claudius, for instance, is often said to have died in 54 AD from eating a dish of poisonous mushrooms given to him by his ambitious wife and niece, Agrippina, who wanted her son Nero to rule.

Polyporus is a genus of fungus that contains large mushrooms that typically grow in woody areas, on or around trees. Some of the species it contains are edible and are occasionally utilized for medicinal purposes. Yet, others types of Polyporus are primarily considered destructive pests. Polyporus betuinus, for example, is a fungus that causes the decay of birch trees in the northern United States.