They may not be your own personal style, but old tires are probably one of the best known items that can be transformed into creative container gardens.
The simplest method is to set an old tire on the ground and fill it with potting mix. Creative gardeners can add their mark by painting the tire with a bold color. Just be sure to clean it first.
To create planters with interesting shapes, use a knife to cut along the sidewall of a tire and then turn it inside out. Tires that have a little bit of give at the area where the sidewall meets the tread work best for this. You can even combine tires to make more elaborate tire planters.