Leucocoprinus cepistipes

Leucocoprinus cepistipes (often spelled cepaestipes), is a species of fungus in the family Agaricaceae. It is also known by the common name onion-stalk parasol in reference to the bulbous stem base. Typical characteristics include a fine-scaled bell-shaped cap, a partial veil, and a tendency to bruise a yellow to brown when handled. It is typically found on wood debris, such as wood chips, but may also grow in potted plants or greenhouses....read more on Wikipedia.