Scott and I installed edging where our sloped front and side yards fall on the sidewalk. Although we would some day love to install a stone wall, for now we're using a cheap & easy eight-foot treated boards and Frame It All landscape edging kits from Home Depot.
While installing the edging, we discovered parts of our front lawn had taken over as much as a foot of the sidewalk. Scott even unknowingly managed to grow some of his plants in just six-inches of soil on top of the sidewalk.
Several people passing-by and neighbors complimented us on our yard. Someone even described the edging as a picture frame around a painting.