JohnI took the time to identify the beautiful and tasty Oxalis spp. which grows in our rented (but pleasingly diverse) lawn. I had assumed Oxalis stricta, but the appressed (vs spreading) hairs on the stem indicate Oxalis dillenii. Fun surprise!
It also shows up in many of our potted plants, which we generally allow — it flowers readily and cheerfully, and the leaves add a tart pop of flavor (provided by oxalic acid, natch) as garnish.