If your lawn contains mushrooms or other invasive fungi that spread rapidly and detract from your enjoyment of the space, there are a couple of ways to remedy the problem. You should only learn methods of dealing with them that will not damage the health of your lawn or that of the surrounding plant and animal life, which will also make your yard a safer place for your family.
First, be aware that the presence of mushrooms can actually be a good thing for the growth of nearby plants and the health of your soil. Mushrooms are the fruiting bodies of underground fungus. They help organic matter decompose, releasing nutrients that are then available for the growth of other plants. A mushroom releases spores that the wind carries to sites where the spores can feed, such as dying logs, leaves and other organic matter. The spores then develop into long threads called hyphae. While hyphae are too small to be seen by the naked eye, you can sometimes large masses of hyphae called mycelium in the soil or beneath tree bark. This mycelium can survive for years, only producing new mushrooms when the conditions are favorable for their growth.
Dealing with invasive mushrooms in your lawn means changing the conditions so that they are not favorable for mushroom growth. Picking or cutting off mushrooms will not solve the problem, as this does not address the mycelium, but it can deter the spreading of spores. Picking and discarding the mushrooms may be a good idea so that children and pets do not eat them, as they are potentially poisonous. Never eat a mushroom you find in the wild; only experts can distinguish poisonous from non-poisonous varieties.
To help deter mushroom growth and manage existing mushroom problems, aerate your soil regularly and apply a nitrogen fertilizer. To break up "fairy rings," circular growths of mushrooms that expand from year to year, you may need to dig down and break up the fungal ring. Remove all infested soil and replace it with fresh soil, then re-seed that section of the lawn. Fungicides are less effective than these integrated organic methods of managing mushrooms.