This is an extremely invasive, although pretty weed. Left to itself, it will take over the entire garden. Spreads rapidly through roots and seeding. Extremely hardy. Stem breaks off easily, so try to remove by the roots if possible. Do not put in the compost - it will even grow there. Throw in the trash. Not to be confused with the common violet, whose leaves are more deeply veined, has longer stems and is more loosely clumped, and whose edges are slightly ridged.
Believe this is a member of the clematis family. Extremely invasive. Likes to twine around other shrubs and vines and smother them. Try to remove from the root. Breaks off easily. Remove anywhere you find it.