Some of the most interesting plant containers are ones that were not originally intended for the purpose.
A few I months ago I bought supermarket salad greens in a clear, shoe box-size plastic container, with a separate lid, and, after eating the contents (which, oddly enough, were packed in a cellophane bag), resisted bringing the container to the recycling center because it seemed there just had to be some way I could reuse it . . .
The other day, it came to me: I punched a few holes in the bottom of the container and then filled it a little more than halfway (3 to 4 inches) with a mixture of compost, soil-less potting mix, and potting soil. With the lid under, I poured water from a glass to almost soak the soil. Because the container is clear, I would see where the water went or didn't. The next morning, I sprinkled mixed greens seeds on the soil, gently spread about a quarter-inch of soil over them, and watered with a fine mist spray (my sprayer is a former window-wash bottle).
Already, two days later, some of the seeds are sprouting! Soon enough, I'll have salad, but not just to eat. The container full of greens will make a great centerpiece on the dinner table. Hey, I may even bring it to work and "pick" my lunch!
What's your best uncommon container idea?