Mushrooms are harmless to your lawn; however, many people do not like the way they look. In addition, since mushrooms can be poisonous, it is beneficial to kill them if you have small children or pets who may eat them. Mushroom spores are located on the tops of the mushrooms (the fruits) and spread easily. Even if you get rid of the mushrooms, the spores may have been released. In general, mushroom spores are not easily killed and fungicides do not usually work.
Pick the mushrooms as soon as you see them. Mushroom spores are released and blow away when disturbed, so pick them carefully. Use a plastic baggie, such as a sandwich bag, and stick your hand on the inside. Pick up the mushroom with your hand in the bag and quickly turn the baggie inside out. This step will not solve your mushroom problem, but it will help control their spread.
Remove organic matter that is decomposing in your lawn. Mushrooms usually grow on or near organic matter, such as logs and dead tree roots. If you get rid of the organic matter on which the mushrooms are feeding, the mushroom spores will be unable to germinate and grow into mushrooms.
Apply granular fertilizer that is high in nitrogen to help speed up the decomposition of any organic matter that you were unable to remove. According to the University of California, apply 6 lbs. of 16-6-8 fertilizer or 4 lbs. of 27-3-4 fertilizer for every 1,000 square feet of lawn to help get rid of mushrooms.