The first is a nipplewort, Lapsana communis, and the second is Gallium aparine.

Gallium but not aparine. The flowers are too large and too white. Some other member of the bedstraw family. Depends which species are around in your area.

Thank you gardengal and floral! I’m happy to learn that these plants aren't problematic in my area. I agree with floral that this galium isn’t aparine. This season produced a bumper crop of galium apartine. It is absolutely everywhere (as was garlic mustard) and it has a different habit - floppy and prostrate. I missed bloom time, and the only one I saw in bloom definitely had much smaller flowers. When I have a moment, I’ll try to id the species of the galium I asked about.