Peziza arvernensis, commonly known as the boring brown cup fungus or fairy tub, is a species of apothecial fungus belonging to the family Pezizaceae. The ascocarps appear as cups, growing up to across. Their exterior is pale tan and the interior is brown. Peziza vesiculosa and P. violacea are similar, young specimens of the latter having a violet hue.
This species often appears in small groups on soil in broad-leaved woodland, especially with beech. It is widespread in Europe with a few records from North and South America.