Try asking your local nursuries to donate items. Let them know you will list them in your next school letter acknowledging the donation. You might even ask that they do the project themselves and put a small sign in the area giving them the credit for doing so. You could also have the kids winter sow seeds for the project.

Send a letter home to parents asking them for donations of plants or bags of dirt. Many people have extra plants or can make divisions and would be willing to donate a few for the school garden. Especially if you explain the educational benefits.

This may not help you now, but later you could introduce some botanical lessons by showing them how to propagate the plants to make more. Once you've gotten a few for the garden you can use them as stock plants.

Ladybug's seed suggestion is a great idea. You could offer to make plaque with the names of all nurseries who donated plants or materials for the project.

I agree with the previous posts.

You can always come to The Middle Tennessee Plant Swap this Saturday and we'll hook you up for free!!!

Thanks to all of you for the ideas. I will pass them on to our group.