To brighten your home this spring, pop a pretty plant in a green glazed container. Cloverlike ornamental oxalis is widely available at nurseries and florists in 3- or 4-inch pots around St. Patrick’s Day. Known by the common names wood sorrel and shamrock, ornamental oxalis has delicate white or pink star-shaped flowers that peek above shapely green leaves. You can plant it outdoors later on, but beware: It spreads, especially in moist, shady spots. Other plant options for a green-on-green effect include lime thyme or Lamium maculatum ‘Golden Anniversary’.