Lawn mushrooms or toadstools are caused by the mycelium fungus, and while not harmful to your lawn, they can be unsightly. Removal can be cosmetic, or the root cause can be sought and corrected, preventing the spread or recurrence of the mushrooms. Lawn mushrooms and toadstools are more prevalent in the fall when the weather cools, the sun is less intense and lawns are consistently moist for longer periods. But the spores can live in the soil and hatch for years.
Mow down the mushrooms using a catcher on your lawnmower to prevent the mushroom spores from being ground up and redistributed onto the lawn surface. When there are just a few mushrooms, this is usually sufficient.
Remove localized, large and/or persistent bunches of mushrooms by determining their food source. This is most commonly buried decaying roots from shrubs and trees previously located there but never completely removed. Dig down under the mushrooms and excavate the decaying root material, lifting it out of the soil. Add fresh soil to fill the void and re-seed or sod the area to restore it.
De-thatch the lawn when the mushrooms appear in high volume and are spread over a wide expanse of lawn. Rake up the excess dead thatch to prevent water and nutrients from being trapped in the dead tissues and kept from the root zone. Removing the moist dead grass will deprive the fungus of an ideal breeding ground. Run the de-thatching rake over the lawn according to the label directions at least twice per year, in the spring and early fall, to prevent or diminish recurrence.
Treat ring colonies of mushrooms and dying grass called fairy rings by using an aerating tool. Pull up plugs of congested soil and mushroom tissue all over the fairy ring area and discard the little plugs of soil, thatch and mushroom into the trash. Water and fertilize the area to feed the root zone and support vigorous grass plants.