There is a wild weedy geranium that grows everywhere. It looks like this: Carolina geranium

Thanks, Alicia!
That's exactly what I have growing in that garden. It's kind of a cute little plant. It's too bad the flowers are so tiny, otherwise I might have considered letting it stay. But then, of course, it would have ended up everywhere...

It's attractive now while it is small, but then it sprawls horribly, the leaves get coarse and widely separated, and it takes over the garden - I had the same thoughts about how pretty the early leaves were when I first saw it after I moved here. DON'T let it grow up!!!