Making my Own Dry Rock "River" Bed

During the course of gardening, I have the fortune (!) of finding some nicely sized cobblestones in the dirt.  They are part of the indigenous soil and are there because a retaining wall we replaced brought them up from deep below.  By placing them in a small sloping area, I have created a nice visual along the stairs and also came up with a way to slow heavy rains from running down this area too quickly.

Note to Garden:  I'm done with the path so please, no more cobblestones!