Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Core eudicots
Order: Caryophyllales
Family: Caryophyllaceae
Genus: Arenaria
Species: Arenaria verna
Cultivar: Arenaria verna ‘Aurea’
Synonym: Sagina subulata 'Aurea'.
Common name: Golden Irish Moss, Golden Moss Sandwort, Golden Sagine, Gold sandwort.

Arenaria verna ‘Aurea’ has bright yellow-green mossy foliage to 5 cm high. During summer it has little star-shaped, white pinhead flowers that are borne singly but are often numerous enough to nearly cover the plant. It used as an attractive dense ground cover filling in spaces between rocks, on walls or between walkway pavers.

Arenaria verna Aurea-001.JPG 

Thanks to Wikipedia for text and information: