Coneflower/Echinacea is an old favorite and can be completely neglected, they will grow anywhere in full sun. Even in poor soil. They also spread nicely. Looks nicely when paired with Russian sage - blue and pink
Place bulbs shoulder to shoulder across the surface of the soil, leaving no space between them. Then top off with more potting soil so the bulbs are just slightly below the surface. Water each container thoroughly, and finish with a layer of mulch.