A fairy ring is an arc of mushrooms, and in fact, is one of the mushroom varieties that can harm your lawn. As the fungus grows beneath the soil surface, u003cstrongu003eit takes up all the nutrients and water from the soil, starving the grassu003c/strongu003e. Because of this, there’s dead grass over the growing edge of the fungus. In general, the fairy rings appear in places where old tree stumps have been removed.