Two plants are blooming, each the color of sunshine. One pokes through the fence from its special spot in a front yard. The others live on the edge, literally, between the fence and the street. Although they put on a show as cheerful as that of the fenced in jasmine, the dandelions are unwelcome. Their relatives on the lawn inside the fence have been, or will be, vigorously exterminated. We decide what is a weed and what is a desirable plant. But any three-year-old realizes that there is just as much joy to be had in a fistful of dandelions.