One more? it seems to have a bit of a trailing habit but not so much a vine.

Is it a purchased plant or something found in the wild? My first thought was possibly Japanese Knotweed (Reynoutria japonica) which is an invasive weed.

More leaf images: https://www.google.com/search?...

Maybe plain green Houttynia cordata?

sooby said:Maybe plain green Houttynia cordata?

Ditto on fish mint.
Supposed to be edible, but smells too nasty for me to even try.

Looks like houttynia to me also. Crush a leaf and see if it has a really sharp fragrance.

Yes! Thank you all! I do remember hearing the mention of "chameleon" when I first saw it. After reading a bit about it I think it's best to leave it in a pot? Sounds like it could be as invasive as running bamboo.

It depends on your location. It spreads for me, but has not jumped beds. Others seem to battle it more than I do. I don't care for the smell, so I keep janking it up, but I'm not tweaky about totally eradicating it from the one bed it is in (hostas and heucheras).