If you want that particular strain, you may need to find it at a gardening center, since it may not come true from seed. I have bought seeds from Thyme Garden and they carry mixed creeping thyme, very low creeping thyme, and one they call 'Magic Carpet', also around 1/2" tall.

Here is a link that might be useful: Thyme Garden

Try this search. (Unfortunately you'll find any page that contains both words.)
http://www.google.com/custom?hl=en&client=google-coop-np&cof=FORID%3A13%3BAH%3Aleft%3BCX%3AVegetable%2520varieties%2520for%2520gardeners%3BL%3Ahttp%3A%2F%2Fwww.google.com%2Fcoop%2Fintl%2Fen%2Fimages%2Fcustom_search_sm.gif%3BLH%3A65%3BLP%3A1%3BVLC%3A%23551a8b%3BGFNT%3A%23666666%3BDIV%3A%23cccccc%3B&adkw=AELymgXKKcoj8ExjLwA_2QQUrTOC56hT5csg6nztOXomwH8QqjOuDih_7udDMbvIgLtF5VsgbKHSInqxR4nHxAwQ_0whzhEXXL9uATYXLPKd8h_o-a-yOzkd46y21DaRePcq3852tVK6X7nnQOMrOZPm4Cm5kLSxSQ&boostcse=0amp;q=elfin+thyme&btnG=Search&cx=003472780514561857771%3A_eyckfdgfmi

It's a special Google search for seeds which I copied from a message board and saved as a Firefox bookmark. I don't know if the seed search is generally available from Google, but you can always do what I do: save this search, then when you want to use it, delete the current keywords and enter a new search. Can't live without it.