Hmmm. I do have wisteria nearby, and yes, it is a vine that grows up trees. I never thought of it as a vine growing along the ground, but that makes a lot of sense. Thank you!

Now, the wisteria leaves on the tree nearby are somewhat larger, and they're also noticeably scalloped, which these are not. But maybe that's just a maturity issue.

Um, this was in answer to a comment that used to precede it. Funny how posts seem to dance around in post time!

Well, no. The grass that it's goring on is not a maintained lawn. I did call it a lawn, but only because I mow it every once in a while. More like grass groundcover. But yes, if this stuff starts appearing on a maintained lawn, it's time to remove it.

Are the stems woody or tough herbaceous?

I guess I would call them tough herbaceous.

Wisteria becomes woody after the first season for any stem, and it sounds like the leaves are different, so I might do a bit more investigating, looking for other vines likely in your area with compound leaves. Check the base of these to see if they are woody. Wisteria certainly are prolific seeders as well as spreading by underground roots and suckers.

If it grows in your area, compare to Apios americana.

These vines growing along the ground are new vines. As I said, probably immature. But the fact that the leaves are subtly different is a bit puzzling.

No tubers evident. But I'm more convinced about Wisteria. The youngest several feet of the vines have smaller leaves that are not scalloped, but when you pull the vines back, the older parts with larger leaves have them scalloped, just like the Wisteria growing up the nearby tree. Evidently the scalloping is something that develops as leaves mature.