Variegated Liriope
Variegated Liriope is a popular choice for a natural edging or border. It is very durable, even taking a trampling without issue.
The light strap-like foliage makes a good contrast against other green plants. Forms neat clumps that enlarge over time without sending out runners. In other words, it stays where you put it.
It shows the best color in full sun, but partial shade is okay too.
In late summer, the plant sends up multiple slender spikes of purple-blue grape-like blooms.
Evergreen foliage 9-12 inches high. Looks best if you give it a “haircut” before the new foliage starts coming up in early spring.