Tricholoma populinum, commonly known as the poplar tricholoma, sandy, or cottonwood mushroom, is a mushroom of the agaric genus Tricholoma.
It was formally described by Danish mycologist Jakob Emanuel Lange in 1933.
The tannish cap is up to wide. It can have radial streaks and a lighter margin. The stem is up to long.
The species can resemble the poisonous T. pessundatum, but can be distinguished by it association with cottonwood.
It is common in western North America, growing with cottonwood and poplars near rivers and in sandy soil.
It is edible and traditionally eaten by the Salish peoples in British Columbia.