Looks like violets to me, which can form a nice groundcover, but will spread quickly to the lawn if you are not careful! Very tricky to get rid of completely; management might be the best course. Fall is a good time to apply herbicides...

They are violets. I have tons of them in our yard. Many years ago I planted them on empty spots around our foundation. They were growing all over the lawn so pulled them out & moved them. I love their flowers though brief in the spring especially the white & violet ones. They do get out of hand & spread. Some of mine have very large heart shaped leaves. They do go really nice with pachysandra which is another great ground cover.

I have them everywhere as well... But I look at them as a beautiful addition to my yard and garden... Lovely flowers, very nostalgic looking.

Ok, they are nice and all but not in my lawn. What is the best way to remove them?

Getting rid of wild violets from growing in the lawn is one of the most difficult gardening problems. To control or kill them can take years since they don't need flowers to reproduce. There are herbicides to use but repeat applications are usually necessary. Also just make sure they list "wild violets" on the product. One of the problems using chemicals are brown spots on the lawn where it's been applied.
The best advice for wild violet control is a thick & healthy lawn preventing them to root. You could also try pulling them out if you don't have a lot. Checking with a local landscape company may have better methods to remove wild violets.

i think they are "dollar weed" or pennywort plant. They are very good for juicing and have many health benefit. I am very happy if i could have some. Please let me know if you want to get rid of them at 214-505-4626 or kttran_2005@yahoo.com