Trees, Shrubs and Conifers: Blank space, 1 by Pseudo

Pseudo wrote:
I'm looking for a ground cover to fill this spot, which is about 8' deep and 10' wide. I don't want it to get over about 1' high since it will be in front of the Dwarf River Birch. What's the point of growing a River Birch if you can't see the bark?

It's full sun and very well drained soil. I know Juniper is going to be mentioned, but I'm hoping to steer clear of that since there are already a bunch of them around this site.