I think you have lamium...as to whether you want to call it a weed or a groundcover depends on a lot of things! Here is a link that might be useful: some varieties of lamium

No, it's a weed that is a royal PITA. Here's the Wikipedia page: https://en.wikipedia.org/wiki/Persicaria_maculosa. You can't compost it, as the roots and stems don't die. There are great groundcovers out there, but this isn't one of them.

yes, it totally could be. This house had a well tended garden, but in the last couple years I think the owner had some health issues, and we all know how fast weed can take over. I was curious so I let it go, one of the few I did let go. I can't see the leaves at all, they are under the cover of the hosta, and I don't think they are very attractive. But, that particular yellow colored bloom and flower shape seems to look nice to me with the lupine. I'd like to try and emulate that look with something with nicer foliage. If anyone has any suggestions as to what my bloom with the lupine and resemble that sort of color and light, airy, flower, I'd love to hear them. Thank you linaria_gw!

Verbesina species? Perhaps Verbesina alternifolia