Further, the mushrooms you see are the fruiting bodies of a much bigger fungus organism under the soil. Most fungus organisms help your grass be healthier – so I’m usually glad to see a few mushrooms in my lawn how to fix patchy grass now and then. The mushrooms are usually gone as soon as things dry out a bit. In the horticultural world “rot” almost always mean “composting”. If you get just the right mix, you get hot composting happening.