Halloween/Fall centerpiece idea: wrap ribbon around small pumpkins - cute and easy. Could make this into a new Halloween tradition. Instead of carving pumpkins, get ribbon scraps and buttons and things together, and decorate small pumpkins.
Spray-paint the rind a matte black and let dry. Use a spoon handle to scratch away paint to create stars, moons, and spirals. Add water and blooms. (via Pumpkin Decorating - No Carve Pumpkin Decorating Ideas - Good Housekeeping )