First image shows Herb Robert, sometimes called Stinky Bob. As you can see, it seeds profusely! A noxious weed in some areas.

See this: http://www.kingcounty.gov/environment/animalsAndPlants/noxious-weeds/weed-identification/herb-robert.aspx

The plant at the left in the 2nd image appears to a oxalis. If so, it's also a prolific weed. It shoots its seeds at least 6 feet from the plant.

Cool.. thanks very much. I have no idea how they got into my yard. :(

Sorry, Phyllis but I disagree with both those ids. If they had been that easy I would have answered earlier. The first is definitely not Geranium robertianum. The leaves, stems and roots are entirely different. If you Google that species you will see.

Nor is the second Oxalis, in my opinion. To me it looks more like a Trifolium or other species in the Leguminosae but it is difficult to be certain because the leaves are folded and the angle is a tricky one.

I suggest you repost the pictures on the Name That Plant Forum where a lot of skilled plant identifiers hang out. Name That Plant