Mushrooms sometimes called toadstools, are the reproductive (fruiting) structures of some kinds of fungi. Most fungi in lawns are beneficial because they decompose organic matter, thereby releasing nutrients that are then available for plant growth. Mushrooms found in lawns often develop from buried scraps of construction lumber, dead tree roots, or other organic matter. These mushrooms usually are harmless to grasses, but some people consider them unsightly or want to get rid of them because young children play in the area. Fungi generally survive in soil for years and only produce fruiting structures when conditions are favorable, such as after periods of prolonged wet weather. This is why during the spring, when rain is prevalent, mushrooms are common. Since mushrooms are merely the fruiting bodies of fungi, removing them does not kill the underground mycelia from which they are growing. That will only occur with time as the source below decomposes.