Your first picture is of Chamberbitter. This weed is mainly seen in the later part of summer. Any herbicide sprayed on it should be mixed with a surfactant (sticker) or else this weed will simply shed all the liquid. Brand name Dismiss has proven effective. Regular 2,4,D based products have not been effective. I’m sure you could use glyphosate (round-up) but you risk overspraying and killing your host grass.