Mushroom “Fairy Ring” 

Fairy rings are circles or parts of circles outlined by mushrooms. The filamentous underground body of the plant absorbs nutrients from the soil, and when they are depleted in one area, the growth then spreads outward, toward fresh regions, leaving nutrient-poor soil in the center. Eventually, such centrifugal growth can form circles over 30 feet in diameter. Much folklore surrounds fairy rings, the general sentiment being that humans who enter or damage such rings risk the fairies’ wrath and suffer all sorts of disagreeable consequences.