A mushroom is the fruiting body of a fungus, the part of the fungus that is designed to release spores into the air. Since the visible mushroom is only the fruit, and not the whole organism, mushrooms will regrow given enough time and if the fungus survives.
Mushrooms are used extensively in cooking in many cuisines. However, many mushrooms are poisonous and eating them can be fatal. Picking your own wild mushrooms is extremely risky and a practice not to be undertaken by amateurs.
Psilocybin mushrooms possess hallucinogenic properties and are commonly known as "'shrooms".