Fairy Ring

I'd heard of these, but before today,

 had never seen one, a fairy ring.

Also called fairy circles, elf rings or pixie rings.

Fairy Rings are naturally occurring rings of mushrooms.

There were several in the hay field, half hidden under the alfalfa,

 and I almost missed them, until I noticed a pattern of arcs.

Elfin toadstools

Folklore says that a fairy ring appears when elves gather and dance.

They are also considered gateways to elfin kingdoms.

Hmmmm...