Oxalis acetosella (Wood Sorrel)

OOO That looks like what my family calls "sweet clover" except that "sweet clover" has little yellow flowers that are decidedly un clover like. I suspect "sweet clover" is not the correct name, as it is not sweet and about the only thing it has in common with a clover is that it has three leaves The leaves are identical to that. It's quite tasty, I've been known to just pluck it off of the ground and eat it. It tastes great if you are thirsty too

 

I will try to get a pic of "sweet clover" if I can find any on my property, I doubt I'll find any blooming though we have lots of the stuff (usually blooms a bit later than this and stays blooming all summer pretty much.)

I would expect you to be meaning Melilotus officianalis.The Wood Sorrel tends to hide away in verdant hedges , what is your plants growing habit?

Between cracks in the sidewalk is the first place it appears (there is some starting to grow, but it is early yet for it) and really, anywhere in the yard as well. Of course it isn't growing for long once my chickens find it, or once I find it if I happen to be hungry

Looks like a very secretive/hard to recognize plant, no wonder it's elusive.