I don't like the stone curbing I see a too often usually beige about a 12-18" tall or in tiers, looks soo un-natural and I'm sure cost a few bucks.
It's also more work to do changes.
When we do ours I plan on the black vinyl or steel, when installed at the correct height looks nice, but to each his/her own....
I also saw this option
Interesting read
.