Apothecium 5.0-10.0 (12.0) cm broad, sessile, cup-shaped, often irregular in outline, eventually spreading; margin incurved, then upright, finally level to recurved, crenate to lacerate; hymenium concave, even to wrinkled or furrowed, glabrous, light brown to chestnut-brown, sometimes tinged reddish-brown; exterior surface white to ash-grey, finely tomentose to furfuraceous; context thin, brittle, colored like the surface; odor and taste mild.
Spores 16.0-18.0 x 9.0-11.0 µm, ellipsoid, smooth, thin-walled lacking oil droplets; spores white in deposit.
Scattered to clustered on well-rotted logs, sawdust, or near decaying wood chips; fruiting throughout the mushroom season; widely distributed and common.
As indicated by the species epithet, Peziza repanda typically expands broadly in age. This feature and a preference for fruiting on or near rotting wood are important but not infallible fieldmarks. Similar colored Pezizas are unfortunately common. Most require a microscope to identify with certainty. Several reported to occur in California are listed below. Peziza varia mimics Peziza repanda with a spreading form and association with rotting wood, but differs in its smaller, greyish-brown ascocarps, and microscopically with septate paraphyses, and a strongly stratified context. Peziza arvernensis, (=Peziza sylvestris), has an ochre-brown hymenium, lighter-colored, slightly furfuraceous exterior, finely warted spores, and fruiting habit on soil and decaying wood. Peziza domiciliana is found on old masonry, rotting textiles, and sandy soils. It forms a tan to ochre-brown cup, sometimes with pinkish to vinaceous tints, has smooth spores, and septate paraphyses; Peziza badia has a dark-brown hymenium with a dingy reddish-brown, pustulate, outer surface, remains cupulate at maturity, has roughened to sculptured spores with 1-2 oil droplets, and occurs on soil in woods; Peziza vesiculosa is an ochre-brown species distinctive for its urn shape at maturity and preference for fruiting on straw enriched with horse and cow dung. Furrowed specimens of Peziza repanda should also be compared with Discina perlata, a snowbank species which bears a resemblance, but differs in a relatively thick, blunt margin and usually short, stout stipe.