Chestnut mushrooms , also called cinnamon caps and fat Pholiota, are known as numerisugitake mushrooms in Japan. 
They’re saprotrophic that, in the wild, grow in dense clusters on rotting wood. 
These mushrooms are not to be confused with a darker version of the common brown, button or cremini mushrooms (Agaricus bisporus), sometimes marketed as chestnut mushrooms because of their shape and color.
Chestnut mushrooms’ caps have brownish scales, with frilly white veil fragments when young, and often look slightly shaggy.