This sprang up in a bed of myrtle near my front walkway. It seems to have spiral opposite wavy or slightly toothed leaves, tiny pink flowers with white sepals in a corymb (?). It bloomed in mid- to late-September.
It is short, not reaching more than 6" or so. The deer seem to like it, as the other couple plants have no flowerhead and the stalk is bitten off.
Thanks!