Virginia buttonweed (Diodia virginiana ) is an incrisingly prevelant weed in our area. It starts growing in early Summer and continues until frost. It is a perennial and can spread by roots, shoots and seed. The seeds are buoyant and water helps spread this weed. Often Virginia buttonweed are first seen in the lower parts of the yard and if not delt with can spread !
Now, how to get rid of this stuff ? The easiest method is to simple hand weed but if you do this be careful to get as much of the root as possible to maximize control. Yes, you will have to do this through out the Summer and probably again next year.
The other option is the use of an approved herbicide which also may require repeat treatment to control. Of course, I believe that herbicidal control is best unless you have a student availabel and wont be heading back to the class room until August in which case, make them work for room and board 😉