Oxalis stricta

Called Yellow Wood Sorrel, among many other names, Oxalis stricta is a native of this area although it is considered a weed by most people if it grows where they don't want it to.  The above specimen is growing in what was my lawn.  We've let the lawn die to save water while we contemplate designing a xeric landscape.  Maybe if we do nothing we'll get an expanding crop of the sorrel.  It's a very pretty plant.  It produces seed pods which at a certain degree of dryness will pop open and send the seeds flying every which way.  It's fun to catch them just before that happens and apply a little pressure so they'll pop in your hand.  Back a few years in this blog I've posted photos of the seed pods.  And there's always Wikipedia.