The only reference I see on the internet for an
Antennaria cv. called 'Silver Carpet' is from a place called Harlequin's Gardens (
http://www.harlequinsgardens.c...), so it doesn't seem to be a recognized cultivar name... though it is clearly an
Antennaria sp.. Is that where you go it from? It may be, in essence, a name they've applied to the
Antennaria species they sell to make it easier to move - who knows.
Anyway, there is a vast number of
Antennaria species and they are difficult to identify. How tall do the rosettes and flower stalks get? A side view of the flowers to show the bracts would be helpful, as colour tipping on the bracts characterizes some species.