Cushion buckwheat is the quintessential cushion plant (hence the name), forming a tidy lump of foliage that helps it conserve water in extremely cold, dry and windy conditions. The silver paddle-shaped foliage gives rise to popcorn-ball shaped flower heads on slender stalks in early summer. The flowers range from white to light red, and are an interesting addition to a sunny rock garden. The only thing cushion buckwheat will not tolerate is soggy soil, so plant it on a slope if that is a concern.