What would your kids think if you gave them all a fully grown big proper pumpkin to carve and take home next year? I bet they’d be impressed. And the thing is you can actually do it for (nearly!) free.
How? Grow your own! A few teachers I know do this, and whether you are at a public or private school it makes a fantastic nature project during the year and is a major plus point with the parents. Growing season starts in early Summer, so get the date in your diary now!