Instruct them to give the bride anything they like, as long as it fits in the jar. Some items may be rice, beans and other non-perishables for the new couple's food storage. Perhaps books of matches, spices, staple food items, etc. Candies are nice and still fit in a jar. For the cooking-impaired bride, invite guests to the shower, asking them to bring their favorite recipe and some sample of it.
Guests can cook up main courses, tasty side dishes or mouth-watering desserts.
Not only will the bride have the recipe, she will also know what is tastes like and how the end results are supposed to look. You could turn this theme into a game by awarding ribbons for best dishes. In the invitation, give each guest a different movie title to use as a gift idea. Pass out bags of popcorn, theater candy and soft drinks. Decorate with movie posters.