SNOW IN SUMMER - Cerastium biebersteinii (Seed - Packet 300mg.) Mat forming wildflower growing up to 12 inches; white flowers with notched petals, about l inch wide; blooms from May through June sometimes later. Just like a carpet of snow! SUN/PARTIAL SHADE
'Silver Star' Dianthus - Add sweet fragrance to garden containers with the perfumed petals of 'Silver Star'. This snowy-white dianthus bears semidouble flowers in May & June. Blooms feature white-fringed petals with a deep cherry-color eye above blue-green leaves. The growth habit of this dianthus is compact & mounding, making it ideal for the front of a border. Name: Dianthus 'Silver Star'. GC: Full sun & well-drained soil. Size: 4-6 inches tall, 8 inches wide
Primula auricula 'Double Purple' ~ "Easy to grow, lengthy flowering period. Stunning double purple flowers in spring. Primulas prefer a well drained soil, making them suitable for rockeries and pots. Frost hardy. Grows in full sun to part shade. Grows 20cm high x 40cm wide."
Moss Verbena may end up being your favorite groundcover. It grows between 6 to 12 inches tall, but has a spreading capability of up to 5 feet. It's easy to grow, is drought and heat tolerant, attracts butterflies and comes in blue, purple and white flowers.