Galium aparine - catchweed - and Lapsana communis - nipplewort.

In my parts the common name for the Galium is goose grass. Geese love to munch on it. I've spent many an hour combing/picking those little green burs out of long haired pets ! Mine dies out during the heat of the summer but will come back with a vengeance. Have had some success controlling it by using a weed whacker to keep it cut down before reseeding.

Yep, the galium is not short on common names :-) According to Wikipedia, it goes by all of these: hitchhikers, cleavers, clivers, bedstraw, goosegrass, catchweed, stickyweed, sticky bob, stickybud, stickyback, robin-run-the-hedge, sticky willy, sticky willow, stickyjack, stickeljack, grip grass, sticky grass, bobby buttons, whippysticks and velcro plant.