We think this is an invasive plant but not either species of Horehound in this case. Its foliage shape, texture, and growth habit resembles Perilla (it goes by multiple common names), which is a member of the same plant family but not otherwise closely related. (To be fair, the mint plant family is a huge family, with many native and non-native species.) Plant ID apps aren't always very accurate, though often they're better at higher-level IDs (to family level, say) than they are finer-level species IDs.

Perilla is widespread in Maryland; there are very few records for Black Horehound, and while the latter is non-native, it's not listed as invasive. The foliage appearance on the pictured weeds don't appear to match the characteristics of horehound foliage, though.

If this is Perilla, then we definitely recommend it be removed. The Maryland Invasive Species Council published a brief article about the plant as the Invader of the Month in June 2011.

Miri