Viola canadensis var. canadensis
Family: Violaceae
Canadian white violet, tall white violet
Viola canadensis var. canadensis image
from USDA Plants website  
Etymology: Viola: a classical Latin name for violets
Plants: erect, perennial, 8"-16" tall forb, mostly hairless
Leaves: basal leaves large, long-stalked, more or less heart-shaped base; stem leaves narrower getting denser towards the top of the stem; usually longer than wide
Flowers: white, 5-parted, 1"-1 1/2" wide; solitary from the leaf axils; blooms April-June
Fruits: elliptic to oval capsule
Habitat: moderate moisture; woods, forests
Conservation Status: Native