One of the henbits; Lamium purpureum or L. amplexicaule. Pretty purple blooms but once you see the purple color you are sure to see it again next year. These are winter annuals that need to be controlled first in the fall and then again in the late winter (chemically, which you can't). Looks like some control has already been applied by maybe extreme winter cold or severe drought??? (scorch on leaves) but not sure. Doesn't seem to do well competing with healthy turf, so overseeding in fall and thickening the turf may be a help.
hortster

Henbit can be controlled without chemicals. Not necessarily rapidly, but eventually.

It's an annual.
So the key to success is to avoid the plants setting seed by removing them. Now.

Handpulling henbit will work because the roots aren't that extensive. The younger the plants, the easier they will be to remove. The youngest seedlings can be hoed, raked into a pile, then removed from the area.

Unfortunately, you'll need to be persistent for an extended time due to the many seeds hanging out in the soil.

Henbits are considered winter annuals, they generally germinate in the fall as grasses go dormant, although a few seeds may germinate in early spring. They do die off in the hot, dry summer weather, prefering to grow in cool moist, rich soils, although they will also do quite well in sandy soils (as I know well). Shallow rooted so easly hand pulled, although tedious if there are many.
Perhaps this link will be of some help.

Here is a link that might be useful: Henbits

Just wanted to thank everyone for their help in IDing my pesky weed...darn those henbits! Given the fact that they are covering about 1,000 square feet at this point along with me being seven-months-pregnant the thought of all that handweeding isn't all that appealing, so I think I'll just remove that sod/weed patch entirely and resod.
Thanks again!
Jen

Henbit can be brought under control with the well-timed application of preemergent herbicides. These chemicals are applied before you see any henbit in your lawn....in the late fall, usually. They prevent the millions of seeds from germinating.

Removing your grass and resodding won't help. The problem is the seeds. Call your local extension office for a good schedule of preemergent timing.