Field Madder, a non-native species, has been added to the USWildflowers database (05/19/2011.)  Scientific name is Sherardia arvensis.  I don’t find an  invasive species listing for this plant, but based on my observation I would use extreme caution in propagating the plant or allowing it to grow in your yard or garden.  It’s also known by the common names Blue Fieldmadder and Spurwort.  Photo below was taken in Walker County, GA on April 21, 2011.

Field Madder, Blue Fieldmadder, Spurwort - Sherardia arvensis