We at McDonald Garden Center are often asked "Do you know what this is?"... and in this case, the answer is poa annua, or more commonly known as bluegrass ~ and yep, this little plant is in fact considered a weed in this area.
Here's what you do to get rid of it:
Bluegrass is a desirable lawn grass in some states, but not here in Virginia. It seeds at a very early age and can spread quite aggressively. In our summer heat, it will die and turn brown, but the seed will germinate in the fall and it will come back. Unfortunately, there is not a selective herbicide that kills only bluegrass and not your desirable lawn, since bluegrass itself can be a desirable lawn in some areas. You can use Killz-all (our form of Round-Up) to kill it, but it will kill anything it touches. The best solution is to use Dimension Weed & Grass Stopper, as this will prevent the seed from spreading. It basically kills seed. Therefore no new bluegrass will germinate, however what is up will remain unless you hand weed or spray it with Killz-all. The more consistent you are with using the Dimension, the less bluegrass you will see.