Cerastium alpinum var lanatum 

Tight fluffy silvery low mats for full sun. Flowers are a bonus but not needed.  

Alpine Mouse-ear Chickweed. A hardy perennial chickweed, when grown in full sun in well draining spots it is a furry cushion of great merit, little white starry flowers a bonus but not needed for the enjoyment of the plant. Put it on nasty ground and watch it thrive. 1cm high without flowers.