Perhaps they could decorate a name tag to put on their pumpkin to avoid "identity crisis" when it's time to go home.

We are having a pumpkin patch for the first time this year involving pre-k, kindergarten and first grade. They will get to choose a pumpkin from the "patch" and bring it home. We don't have time to paint it. Any other ideas to keep them busy for 1/2 hour to 45 minutes?