Remove any excessive decaying matter from the soil where the mushrooms appear. Rake scat from pets and dispose of it in a container. If decaying organic mulch is nearby then rake or shovel it up and replace it with fresh mulch. Recycle the old mulch into a compost pile.
Add extra nitrogen in a ready-to-use form to the soil to encourage the area's fauna to more rapidly decompose the soil's organic material. Apply 1 lb. of nitrogen per 1,000 square feet of lawn.
Manage the lawn's water better. Mushrooms need a high moisture level to sprout. Consider a drainage system if the water level is constantly high, or water the affected area less than the rest of the lawn.
Dethatch and aerate the lawn to allow air to better circulate over and into the soil. Power dethatchers and aerators are available for rental at many home improvement or hardware stores and operate much like lawnmowers. Rake a small area with a hand dethatcher. Hand aerators punch holes in the sod with foot pressure similar to a shovel.
Pick the mushrooms as they appear to prevent them from releasing more spores into the lawn.