How to identify it?
Cap
Cap 6-20 cm across, nearly round at first, later domed to flat; white to cream; surface smooth or finely scaly; bruises yellow. Flesh thick, firm, white. Odour and taste not distinctive.
Gills
Gills free, pale grayish pink at first, turning chocolate-brown, crowded.

Scientific Classification

Phylum
Club fungi Class
Mushroom-forming fungi Order
Gilled fungi Family
Agaricaceae Genus
Agaricus Species
Horse mushroom