I've got some kind of shrub that spreads by runner roots popping up all over my yard that I can't id.

first pic - it seems familiar, does it die down in winter, and grow back in spring?

like elderberry.

Very invasive non-native. Kill it before it lays eggs, LOL!

but the second picture had me wondering. It looks more woody than I have ever seen in knotweed.

But you are right, get rid of it!!!!

i had pulled some of this, and left it on the ground to dry out a little before sending it to compost. in the meantime one of the pups found the stems crunchy and interesting, and chewed on several. he then suffered several days of diarrhea. coincidence?
read some stuff about getting rid of this. pain. but....

The plant has a long history of use in traditional Asian herbal medicine as a laxative.

I have a clump of it I keep because it's an awesome honey plant, but the stuff is hard to control and invasive. Overall, you're probably better off getting rid of it.