Common Fieldcap (Agrocybe pediades)

Agrocybe pediades is a typically lawn and other types of grassland mushroom, but can also grow on mulch containing horse manure. It was first described as Agaricus pediades by Swedish mycologist Elias Magnus Fries in 1821, and moved to its current genus Agrocybe by Victor Fayod in 1889. A synonym for this mushroom is Agrocybe semiorbicularis.

Source: https://www.inaturalist.org/observations/129049713