The lawn beneath your trees can be patchy at best. To improve the eyesore dircle your tree with some edging, throw in some potting soil and plant Gaillardia. This friendly flower has lush green plants in early summer, blooms bright from July through October, and multiplies to fill in landsacape areas. It comes in the traditional yellow/orange seen here, or a cool purple variety. It tolerates the shade beneath your trees and seems to flourish even when competing for nutrients.