Looks like some sort of Amaranth spp. It's a vegetable just as the Taraxacum officinale in your first photo is. So it's quite likely to be an adventitious weed that will grow in disturbed soil, but is also actually eaten by people in various places. Unless you are adventurous and use several sources to ID this as edible, you are better off pulling them up and discarding before they drop seed.
