I have one with herbs in it - oregano, mint, thyme, sage. The oregano, thyme and mint spread pretty easily so they aren't really effected if the soil level changes, they're pretty adaptable. The sage is a shorter term perennial but doesn't seem to mind either. It's also a good way to contain...
I did some hugelkultur beds a few years ago in my garden. I had an old woodpile I needed to get rid of as we no longer use the wood burner for heating. I didn't do anything so fancy or as pretty as their metal beds as the goal was to get rid of old logs and save money so not buying anything. I...