Here is a link to information about identifying mushrooms: http://edis.ifas.ufl.edu/ddis3. This publication also mentions the “death angel” mushrooms, the Amanitas. There are 15 or so deadly mushroom species and about 100 poisonous mushrooms.

There are several thousand species of mushroom and they adopt a wide variety of shapes. Mushrooms are fungi. The mushroom part that we pick is the fruiting body. This is the part that carries the spores for reproduction. The mycelium is the portion of the mushroom that lives in organic matter. Picking the fruiting body of the mushroom is like picking the flower from a bush. The bush (mycelium) remains to produce more flowers (fruiting body). Just as flowers produce seeds, the mushroom’s fruiting body produces spores for reproducing.

These fungi are important in maintaining the biological balance of nature. Saprophytic mushroom species use many enzymes to break down much of the organic matter in the soil. Saprophytes can grow in the soil, on dead branches, cut wood or tree trunks. There are also symbiotic fungi which are very important in the forest. The mycelia of these intertwine with the roots of young trees forming mycorrhiza. This benefits both the tree and the fungus. The fungus makes it easier for the tree to obtain minerals from the soil and the tree produces organic matter which helps the fungus grow. Most forest-dwelling mushrooms form mycorrhiza.