Polygala sanguinea

Polygala sanguinea, known as purple milkwort or field milkwort, is an annual plant in the family Polygalaceae. It is native to widespread areas of eastern North America, but is absent from much of the southeastern Coastal Plain. It is it generally found in wet, acidic soils in open areas such as prairies and fields.
It produces pink-purple (occasionally white) flowers in the summer.