Thanks you for bringing this to our bi-monthly plant clinic. I feel certain I would not have been able to identify it without looking at it closely. It appears to be Common Venus-looking-glass or Clasping bellwort, Triodanis perfoliate, which is a winter annual or perennial. Its name comes from the seeds which apparently resembled tiny mirrors. However, the seeds are so small, it is difficult to see the resemblance and very little shine can be detected.
Venus-looking-glass is an American native wildflower found throughout the United states except the Rocky Mountains. The purple flowers are rather striking even though they are small (about ½ inch across). The leaves are alternately arranged on the stem with finely serrated leaf margins. It grows between 6-12 inches in height.
This is one of those instances when one person calls a plant a weed and another person will refer to it as a wildflower. Of course, if it is growing in your lawn then I suppose it is indeed, a weed! You might consider hand pulling it if it is found in the lawn.
Cherokee Indians steeped roots and other parts of plant to make a drink to cure indigestion. The plant attracts birds and is resistant to deer. To ensure higher germination rates, refrigerate seed for 60 days. Venus-looking-glass plants have no special soil preferences and will tolerate drought conditions once established.