I need help figuring out how to cover a small section of our yard exposed recently when we rebuilt our deck. We live in GA so the exposed section is mostly hard red clay, and because it was covered by the old deck, a small portion of it is cement under the red clay. Removing the cement is not an option. This is also a part of the yard that will have high foot traffic straight into our back door. It's about a 5x8ft space. Full sun.

I'd like to put something like moss down, but after researching it sounds like the full sun makes that impossible. River stones were also an option, but may be too expensive.

Does anyone have any suggestions for what we could do to cut down on the mud being tracked in through the back door?