Liriope muscari has grassy foliage and spikes of blue or white flowers in the heat of late summer. It is especially accommodating as an edging or groundcover and there are some varieties with handsome variegated leaves (eg ‘Silvery Sunproof” ).
A good edging plant, and one that thrives in window boxes, hanging baskets and places that need a summer groundcover, is "Portulaca grandiflora."