Calling All Gardeners! Help Me Name This? What Is It?

I've been looking at plants to plant on my back hill for ground cover so I don't have to mow.  I've been considering Lavender, Black Eyed Daisies and some other flowers to plant there as well.. But, in my minds eye, I kept seeing THIS!

And I couldn't find it anywhere or explain to the nurseries what I was looking for until I saw it at BookWalter Last night!  I think it's beautiful and appears to grow in quite thick.

Do you know what it is? The servers there couldn't tell me!

Let me know if you would please. I think it would do quite well on my back hill.

Thanks,

Faith