It's still hard to tell from the pictures as they seem a little out of focus, but I'd tentatively go w/Yvonne's ID of Tradescantia...maybe Tradescantia ohiensis? the close up of the flower seems to have only 2 petals rather than the 3 typical of the species, but maybe it's an anomaly or the petal was removed? Hard to say, again, but perhaps that's it: google image search for the genus and see if it matches what's in your yard.