Violet, Wood - Viola palmata

Viola palmata, also known as Wood Violet or Early Blue Violet, is a perennial wildflower native to southern Michigan and the southern UP. Plant reaches 6 inches tall and flowers from May to June with a purple blossom. It prefers partial sun to full shade, medium to dry soil and will grow in loam or sand.  Especially dramatic in a grouping and spreads well by seed. It is not uncommon for this spring bloomer to flower a second time in the fall. Great for borders, rock gardens, and as a matrix plant around and under taller plants.
 
Violets are the host plants for Fritillary butterflies and provide an early nectar souce.
"In the fall, Great Spangled Fritillary Butterfly caterpillars hatch out of eggs, eat their eggshell, and drop off their host plant into the leaf litter to diapause as tiny hatchlings. Once the host plants, violets, sprout new leaves in the spring, caterpillars will start eating and resume their growth."
From "Where Are All the Butterflies Now".  Side note, the UP is home to one of nine subspecies of fritillary in which the female is a creamy tan instead of orange.