You folk are wonderful. Thank you very much for the confirmation. Now I can start the long removal process. Sometimes I wonder if the guy we inherited the garden from was building a landscape of invasive non-natives!

Looks like some type of Morning Glory (a vine).

Phlox?

I agree with Gardengal. They probably are Sweet Autumn Clematis seedlings. Seed probably blew in from somewhere nearby, or who knows from where. Sometimes seed grown SAC come variable in: growth habit, flower form and size, and abundance of bloom. I have seen tiny, miserable formed flowers on some; vines that refused to climb preferring to trail along the ground; and some that had very sparse blooms. It's always best to take cuttings from a top performer if you want a SAC, and pitch the seedlings. Moses