I would look first do a little research on Thomas Jefferson who was an avid gardener and also research Lewis and Clark. During their expedition, they collected many samples of plants and animals that they found. They also made sketches of many plants. I think you'll be able to gather great ideas for your garden!

I live in Virginia and think that Monticello and Colonial Williamsburg websites would be inspirational. They both sell heirloom seeds. Monticello still sells seeds that are most likely descendants of the plants Thomas Jefferson actually ate. I just think that is so cool!

As far as your climate ... I'm not sure how you keep things cool and moist in a desert climate. Maybe your local extension website would be a good place to start? I have the opposite problem living in a forest. Shade and dampness.

Maybe one of those shade clothes over the bed plus a rain barrel so you can water often?

It's a great idea and your students are lucky to have such a teachre. But unfortunately your AZ climate, soil etc. are so different from the East Coast that I'm not sure it's possible to focus on that.

How about seeing what was grown in that era in AZ--the Indians and the Spanish? You could start with the botanical garden in Phoenix for historic garden suggestions. Good luck.

You may find some useful material for your class in a book called The Lawn; A History of an American Obsession by Virginia Scott Jenkins. The background info about how people used to view their land as a place to grow food and medicinal crops, and how that has changed to almost all ornamentals, would be great for kids in hope that future generations will move more toward embracing and understanding nature, especially in regard to food.

Another book, Redesigning the American Lawn; A Search for Environmental Harmony by Bormann, Balmori, and Geballe brings the focus back to how individuals in particular and communities in general can use resources more wisely. This book is especially pertinent to those in a desert climate.

I think creating a historical garden is an excellent way to make this info tangible and relatable to kids.

Where I live is not considered a desert but we've had drought conditions this year, with more than half of the average rainfall missing. So I have a small taste of the conditions in which you live. I think an important part of your lesson plan regarding this garden would be experiencing how hard it is to grow most traditional edible crops there and how folks at the time dealt with it. Agree with the shade cloth suggestion above and wanted to add that the experience of lugging buckets of water to the garden would make a lasting impression on the kids. I'm sure they'd come away from that with a new appreciation for how valuable of a resource water is in a desert.