Fairy Ring Mushroom

The fairy ring mushroom is the small, tan, tough-stemmed mushroom that produces the true fairy rings in lawns — arcs and circles of darker, faster-growing grass with mushrooms following the advancing edge after rain. The cap is buff to tan, bell-shaped then flattening with a low central bump, the gills are well-spaced and pale, and the wiry stem is remarkably tough and pliant. Dried specimens revive and release spores when they are wetted again.

For a gardener its interest is mostly turf ecology: the ring is the visible edge of a slowly expanding underground mycelium decomposing thatch and organic matter, which releases nitrogen and greens the grass along the arc. Several small brown lawn mushrooms look broadly similar, some of them toxic, so the pale spaced gills, tough reviving stem, and true ring habit are the features to note — and, as always on lawns, the green-spored parasol is the serious hazard to keep separate.