I would recommend setting up a few different stations.

1. Pumpkin Ring Toss: You might be able to get a few pumpkins donated from a local vendor. Try to get ones with large stems. A couple of wooden hoops can be purchases at a local crafts store. Use the pumpkin stems as the target for the rong toss...

2. See of you can get someone to cut out a pumpkin target for a game of bean bag toss. Just get a 3/4" piece of plywood, maybe 4' x 8', and draw a pumpkin. Jig it out and cut out the eyes, nose and mouth for the targets...

3. Freeze Pops: If allowed, the kids love these. Ice cream is another option...

4. Gourd Bowling: Get some plastic bowling pins but instead of using a ball, try a pumpkin or a gourd. The gourd/pumpkin will roll funny, making it more fun, and tougher as well. I do recommend trying to get a fake gourd or pumpkin, as continued use will quickly turn your gourd soft and messy.

5. Maybe a simple coloring station. Print out fall themes picture and have crayons available.

Hope this gets you going.
PresidentJim