Trunk or treat decoration ideas include a monster mouth, graveyard, mad scientist and pumpkins. Another option is a popular character or show, such as Charlie Brown's Great Pumpkin, Angry Birds or Star Wars.
Trunk or treat decorations go into the trunk area to create a themed display. The specific theme depends on the audience of the trunk or treat. If the event is targeted toward young children, scary themes or decorations aren't recommended. Costumes that match the theme for the people passing out candy add to the decorations.
For the monster theme, the open trunk is the mouth of the monster. For a friendlier option, the trunk can look like a black cat. Cardboard painted white works well for the teeth. A red plastic tablecloth is an option for a tongue that sticks out of the mouth.
Fake tombstones from a Halloween store set the stage for a graveyard theme. Another option is to cut the tombstones from sheets of Styrofoam. Cobwebs and giant spiders strung from the corners of the trunk add to this theme.
A portable fog machine is an option for a mad scientist's lab. Dry ice also works to create the steam effect. Other prop ideas include test tubes and warning signs.
A general pumpkin or Halloween theme is an easy route. Real or artificial pumpkins, Halloween garlands, small scarecrows and hay bales work well for this theme.