We have a drainage swale at the back of our yard, and without changing the slope of the terrain, I have turned it into a garden that in the spring is a water garden, and as the summer progresses is more of a dried riverbed.

I would like to keep the look of the garden very natural, but need suggestions on creating an edge between the lawn and the garden. We tried using brick and stone, but the look was too "manufactured" for what we were aiming for. Could I plant a low-growing, non-evasive ground-cover to act as a edger between the lawn and the garden? I have seen it done in magazines with moss, but with full afternoon sun on the area my research indicates moss will not work for me. Can anyone suggest a groundcover? I would also like to use the same in between the stones on the walkway, which gets medium traffic. Any suggestions would be greatly appreciated