Mushrooms, sometimes called toadstools, are the visible reproductive structures of some types of fungi. Most fungi in lawns are beneficial, because they decompose organic matter, thereby releasing nutrients that are then available for plant growth.
Fungal fruiting structures release tiny spores that are easily carried on air currents to new sites. When spores reach a favorable place to grow they germinate. When mycelium has developed sufficiently, fruiting bodies such as mushrooms can be produced. Fungi generally survive in soil for years. They produce mushrooms only when conditions are favorable, such as periods of prolonged wet weather or over-irrigation.
Mushrooms found in lawns often develop from buried scraps of construction lumber, dead tree roots or other organic material. These mushrooms are usually harmless to grasses, but some people consider them unsightly or want to get rid of them because young children and pets play in the area.
Remove the mushrooms as they appear. Removing excess thatch and aerating the soil to improve water penetration in the lawn can help in some cases.
As you know, some mushrooms may be poisonous, do not eat them. Master Gardeners do not identify mushrooms.
For more mushroom information, go to ipm.ucanr.edu; or for more gardening information, go to cecolusa.ucanr.edu. ■