A fairy ring, also known as fairy circle, elf circle, elf ring or pixie ring, is a naturally occurring ring or arc of mushrooms. The rings may grow to over 10 metres (33 ft) in diameter, and they become stable over time as the fungus grows and seeks food underground. They are found mainly in forested areas, but also appear in grasslands or rangelands. However, they are often seen as hazardous or dangerous places, they can sometimes be linked with good fortune.
Fairy rings were thought to mark the site of witches' dancing on Walpurgis Night, and Dutch superstition claimed that the circles show where the Devil set his milk churn. In Tyrol, folklore attributed fairy rings to the fiery tails of flying dragons; once a dragon had created such a circle, nothing but toadstools could grow there for seven years. European superstitions routinely warned against entering a fairy ring. French tradition reported that fairy rings were guarded by giant bug-eyed toads that cursed those who violated the circles. In other parts of Europe, entering a fairy ring would result in the loss of an eye.
Entering the ring on Halloween night was especially dangerous. One source near Afon fach Blaeny Cae, a tributary of the Dwyfach, tells of a shepherd accidentally disturbing a ring of rushes where fairies are preparing to dance; they capture him and hold him captive, and he even marries one of them. Freedom from a fairy ring often requires outside intervention. A tactic from early 20th-century Wales is to cast wild marjoram and thyme into the circle and befuddle the fairies; another asks the rescuer to touch the victim with iron. Other nethods require that the enchanted victim simply be plucked out by someone on the outside, although even this can be difficult: A farmer in a tale from the Langollen region has to tie a rope around himself and enlist four men to pull him from the circle as he goes in to save his daughter.
Mortals who have danced with the fairies are rarely safe after being saved from their enthrallment. Often, they find that what seemed to be but a brief foray into fairyland was indeed much longer in the mortal realm, possibly weeks or years. The person rescued from the fairy ring may have no memory of their encounter with the sprites, as in a story from Anglesea recorded in 1891. In most tales, the saved interlopers face a grim fate. For example, in a legend from Carmarthenshire, recorded by Sikes, a man is rescued from a fairy ring only to crumble to dust. In a tale from Mathavarn, Llanwrin Parish, a fairy-ring survivor molders away when he eats his first bite of food.
Some legends assert that the only safe way to investigate a fairy ring is to run around it nine times. This affords the ability to hear the fairies dancing and frolicking underground. According to a 20th-century tradition of Northumberland, this must be done under a full moon, and the runner must travel in the direction of the sun; to go widdershins allows the fairies to place the runner under their sway. To circle the ring a tenth time is foolhardy and dangerous.