The name for a ring of mushrooms believed to be a fairy dancing ground is a fairy ring.
A fairy ring is a naturally occurring circle or arc of mushrooms, formed as fungal mycelium grows outward through soil. Mushrooms may appear along the living edge of the underground network, sometimes producing a ring of darker grass or, when conditions are poor, a zone of dead vegetation. The rings can expand over many years and may reach more than 10 metres in diameter.
In Celtic, British, and wider European folklore, the circles were explained as places where fairies or elves danced at night. Medieval traditions already connected circular growth patterns with supernatural revels, and the belief continued in Wales, Scotland, Ireland, and England. Some stories promise good fortune, while others warn that entering a ring could trap a person in an enchanted dance or make time pass strangely.
A common mix-up is treating fairy ring as only a magical term. It is also the standard name for a real fungal phenomenon. Fairy circle, elf ring, and pixie ring are related alternatives, but fairy ring is the most familiar quiz answer.