Wild Oxalis, aka Sourgrass
The bane of my existence used to be Shotweed, but the Oxalis is rampant in my garden and everywhere on my property this year. Have always had it but I guess all the rain we've had since Spring has made it grow leaps and bounds. I'm forever pulling the stuff, seems like the next day it's right back! This is the one with the small yellow bloom. Mine can get very tall and almost shrub like if I don't catch it looming under the daylilies. And it seems to love growing under my boxwood hedge.
The wild violets are just as evasive this year despite pulling gobs in the Fall and this Spring.