These started popping up in a very localized corner of my yard about two months ago. The rounded leaves are of course the cotyledons. Now they are showing their first set of true leaves (the pointy ones) and I thought this would be a better time to ID than before. Each cotyledon is about 1-1/2" wide, to give you a better perspective. There are other plants that have popped up recently as well but they were easy to identify, such as beans and tomatoes. This one has me stumped though.
Any guesses?