The edible Coprinellus disseminatus
differs in that it is smaller (under 2 cm broad) and does not become inky when old. The less common Coprinopsis romagnesiana
is similar in that it clusters at the base of trees, also has blackish spore print, and also has a cap that becomes inky. However, it differs in that the cap has a tan ground color as is covered with brown, appressed scales. In terms of edibility and interactions with alcohol, it is similar to this species.
See also Coprinellus micaceus