This delicate spring ephemeral is Erythronium americanum (common names: trout lily, dogtooth violet). They are scattered throughout the woods behind my house,where I took these pictures.
Trout lilies grow from corms and send out stolons from them, forming colonies over time if left undisturbed. They grow best in a deciduous woodland environment, with filtered sunlight and humus-rich soil. They are some of the earliest bloomers in the spring, and by the end of the season, flower, foliage and all disappear, remaining dormant until the following spring.