Function: noun
Etymology: from the folk belief that such rings were dancing places of the fairies
Date: 1599
1 : a ring of basidiomycetous mushrooms produced at the periphery of a body of mycelium which has grown outward from an initial growth point also : a ring of luxuriant vegetation especially when associated with these mushrooms
2 : a mushroom (esp. Marasmius oreades ) that commonly grows in fairy rings