Looks like violets. Viola spp. Don't know how to get rid of it, but it's a pretty common lawn weed, ask at your local nursery.

WW

wild violets. for sure I thought that I liked them and transplanted them into a garden bed. now I am pulling them out!!! if you let them, after they flower their leaves will get huge!

looks like garlic mustard to me. if next year it sends up stalks with white flowers, you've got garlic mustard, in which case you can use it like you would parsley. (i'd rip it all out an burn it, though, since it's a horrible foreign invasive) if it gives purple flowers, it's dogtooth violet like they said. dogtooth violet, while native and not as agressive as garlic mustard, can spread pretty fast. you can collect the flowers and make a very purple jelly with them. or, use them in salads.

not dogtooth, sorry. just plain wild.

me again. it's definitely garlic mustard. didn't notice before that in your picture the leaves have toothed edges. wild violet leaf edges are smooth.