There are different ways that mushrooms can appear in your yard. Mushroom mycelium, which is the part of the organism from which mushrooms grow, can live in the soil for years. Mushroom spores can be blown across long distances. In order for mushrooms to grow in your lawn, either these wind-blown spores or mycelium must be present, along with moist conditions.
This can be the remains of a tree stump, dead tree roots that are decomposing or buried lumber from construction projects. Some of the varieties of mushrooms that grow on such decaying wood products are also the result of poor drainage or overly moist soil conditions. They are not harmful to your grass; mow them off when mowing the lawn. To eradicate them, dig up and remove rotting tree stumps, roots or lumber.
Roots of Live Trees and Shrubs
Mycorrhizal is a mushroom-producing fungi that can connect itself to the roots of trees and shrubs. This beneficial fungi helps trees and shrubs absorb water and nutrients from the surrounding soil. To remove them from the lawn, you must remove the roots of otherwise healthy trees and shrubs, which may cause them to decline and die.
Diseased Roots of Trees and Shrubs
Mushrooms that grow in the grass from the base of a tree or tree stump can be an indication that the tree is hosting a fungus, causing its roots to rot. Unfortunately, the mushrooms only appear after the roots are fully infected and the tree is near death.
Newly Laid Sod
When newly laid sod is becoming established, it requires a lot of water. Consequently, smaller mushrooms often begin to grow in the sod. Once the lawn is established and you cut back on the watering, conditions will no longer be favorable for these mushrooms to grow. These small, cone-headed mushrooms will not harm your sod or existing lawn.