Large caps, initially hemispherical and expanding to broadly convex or flat. The cap is covered in large reddish-brown scales over a whitish, yellowing ground; it slowly turns yellow when cut or bruised.  Smell of almonds.  Spores are purple-brown.   Immature specimens have a delicate white veil extending from the stem to the cap periphery.

There are several similar species - the toxic Yellow Stainer and some inedible related species quickly turn yellow when cut or bruised.

smell

Photo from top and in side view, showing ring and gills, of younger specimen

Various including woodland and roadside verges on humus rich soil, and also often found under conifers.

Autumn.

Widespread and fairly frequent in Britain.

Occasional in Leicestershire and Rutland.

https://www.first-nature.com/fungi/agaricus-augustus.php