These are two different but very similar plants that I had growing quite near each other - both henbit and dead-nettle. Henbit (Lamium amplexicaule, and what I think is the plant in question) has a more apple green leaf that is slightly broader. The dead nettle (Lamium purpureum) while incredibly similar, has a more olive tone to the leaves, the leaves are slightly smaller and slightly more pubescent and the top leaves tend to be reflexed.
Just fyi, I also had the Glechoma hederacea (yes, there's a TON of weeds in Tennessee!) which has a similar flower, a sharp scent (that I found pleasant) when crushed, but is prostrate in habit (the other 2 are upright) and roots easily and quickly along the stem, as well as underground stolons, whereas the other two are more seed dispersed, I believe.... all three of them are quite vigorous, but the first two appear primarily in the spring and the last was obvious throughout the warm weather.
Hope this is helpful.
