I replaced a strip of grass leading off our patio with flagstone pavers. I had wild strawberry growing on my paths and between cracks in my patio. I decided to use it for one stretch of pavers. It has filled in beautifully besides giving sweet, tiny berries. For another stretch I used Viola labradorica and on still another section Tiarella cordiolia. All are doing great. For years I have had a large number of concrete pavers linking the front lawn with the back woods. For groundcover here I have used Green-and-Gold, Chrysogonum virginianum. Spectacular in the spring when it flowers and nice and green the rest of the year.