Fairy rings occupy a prominent place in European folklore as the location of gateways into elfin kingdoms, or places where elves gather and dance. According to the folklore, a fairy ring appears when a fairy, pixie, or elf appears. It will disappear without trace in less than five days, but if an observer waits for the elf to return to the ring, he or she may be able to capture it.
(Source: oldmosswoman)

A fairy ring, also known as fairy circle, elf circle, elf ring or pixie ring, is a naturally occurring ring or arc of mushrooms, in his case Marasmius oreades. The body of this fungus, its mycelium, is underground. It grows outward in a circle. As it grows, the mycelium uses up all of the nutrients in the soil, starving the grass. This is the reason a fairy ring has dead grass over the growing edge of the mycelium. Umbrella-shaped fruiting bodies, called mushrooms, spring up from just behind the outer edge of the mycelium.
(Source: malformalady)