"Oxalis Corniculata", aka Creeping Woodsorrel, Procumbent Woodsorrel, and even Sleeping Beauty is one of many of the woodsorrels that get planted by the birds that eat the seeds the plants produce. Your best defense with this is just a good, healthy lawn although the seeds that get dropped can germinate quite easily. Spraying with vinegar will also kill the grass and most of the rest of the "weed killers" that would kill off the plants now growing are not acceptable to organic gardeners those will not prevent more plants from growing. Hand pulling can be effective although that to will not prevent more seeds from germinating. These are among the "weeds" we will always see.

So my only option is to learn to love Oxalis? Egad. :[