Agaricus abruptibulbus

Agaricus abruptibulbus is also known as the flat-bulb mushroom or the abruptly-bulbous agaricus.

Description
Its cap can grow up to 8cm/3.1 in in diameter, is convex in shame, occasionally containing an umbo, and is whitish in color. Bruising may cause the cap to turn yellow. The stipe contains a large white annular ring. The gill attachment is free. The gills itself are initially grayish before turning brownish after the development of spores. Spores are brown to purple-brown, elliptical, and are –8 by 4–5 µm.

This species is also able to bioaccumulate cadmium from soil.