This plant is called the Arenaria montana, common name – Sandwort. Its other names are Komugisenno (Japanese) and “Montana”.
It has recently become a ground cover of choice especially in small visible areas, under pine trees and in pots around specimen plants. It is beautiful when mounded over in bloom, and looks green and neat out of bloom all through the year too.
Botanica says it’s an ideal rockery plant and that this species is from southwest Europe . The flowers are about 1 inch in diameter, pure white with yellow-green centers.