Lepiota americana

Common Name: None.
Description: Cap 3-15 cm across, oval becoming broadly convex, then flax with an umbo; background whitish at first, then reddening when mature and bruised; dry and smooth but quickly breaking into large, coarse, reddish-brown or dingy pinkish-buff scales. Stem 70-130 by 5-20 mm high and wide.
Habitat: singly or in dense clusters in fields, waste places, and sawdust piles and around stumps. Found widely distributed in eastern North America, west to Michigan.
Edible: Good.

Source: Mushrooms of North America by Roger Phillips.