These charming flowers certainly live up to their name. They can be very abundant in moist woods or shady lawns; this luxuriant patch grew along the Trillium Trail in Fox Chapel, where it was blooming in late April. Another picture is here.
Gray describes the genus and the species:
CLAYTONIA [Gronov.] L. SPRING BEAUTY. Sepals 2, ovate, free, persistent. Stamens 6, adhering to the short claws of the petals. Style 3-cleft at the apex. Pod l-celled, 3-valved, 3-6-seeded. — Perennials, our two species sending up simple stems in early spring from a small deep tuber, bearing a pair of opposite leaves, and a loose raceme of pretty flowers. Corolla rose-color with deeper veins, opening for more than one day. (Named in honor of Dr. John Clayton, one of our earliest botanists, who contributed to Gronovius the materials for the Flora Virginica.)
C. virginica L. Leaves linear-lanceolate, elongated (7-16 cm. long).— Moist open woods, N. S. to Sask., and southw.; common, especially westw. and southw.