Remove the existing mushrooms from the lawn and surrounding areas. While this will not eliminate them, mushrooms multiply by releasing spores into the air to propagate new growth. Removing the existing ones will limit the amount of spores released.
Remove any thatch from the area. Use a rake to remove all items except the grass, plants and trees. Rotting twigs, leaves and other refuse act as food for the fungus. Getting rid of these items will assist in eliminating new growth.
Remove any tree stumps or dead trees from the area. Contact a professional for complete removal. The rotting process of these stumps and trees acts as a food source for the mushrooms.
Fertilize the area with a nitrogen-rich fertilizer. Spread a mixture of nitrogen in the area at the rate of 1 lb. per 1,000 square feet. The nitrogen will speed up the decay process of any item in the yard, helping to eliminate future food sources for the mushrooms.