When we bought our home some years ago, this square patch surrounded by concrete was just filled with crushed limestone rocks and had nothing else in it. Eventually, grass started growing through the limestone and we had to use grass killer since it was scary mowing over all the rocks. It became quite an eyesore. I decided to make it somewhat better looking and started throwing various plants in it. Here are a couple of pictures of what it looks like now. There's still some work to be done, but it looks much better now than it did.