The cap is initially convex then flattens with a broad central umbo when it matures; variable in colour depending on the weather, from tan coloured when wet to pale cream or buff when dry.  The gills are thick and widely spced and pale creamy buff. Often in large fairy rings.

Note that other grassland species may also occur in fairy rings.

Photograph fairy ring, and a specimen from top down, in side-view and underneath to show gills; note substrate and habitat.

Lawns and short grass in groups or 'fairy rings'.

Autumn.

Widespread and fairly frequent in Britain.

Fairly frequent in Leicestershire and Rutland.

https://www.first-nature.com/fungi/marasmius-oreades.php