I use hostas to fill-in the blank spots in my shade garden. They make a great background for white impatients.
The plant is set in a frog and covered with moss. I'm not sure how long it would last without water, but to make it last longer I'd use a small butter tub, custard up, or bowl, and then disguise it with the moss. The silver/pewter tray makes a nice display.
Design and photo courtesy of Eddie Ross