There is many a raised bed system that will serve the purpose, but being the anti-plastic purist that I am, there is only one product that I can wholeheartedly endorse and that is those of Tony Davis at The Farmstead in Leverett, MA. They ship these all over the country so don’t feel like you have to be close to get them.
Made simply of White cedar, you can stack them to help with mobility or create a more dramatic look, and they can fit in almost anywhere. I use them in my own garden instead of spending months of back breaking effort eliminating all the rocks.
The bottom picture is an herb garden tucked in behind an old New England tavern that gives a place for the chef the grow fresh goodies for the restaurant.