I got two small pumpkins for less than $2 each at Trader Joe's. I found some moss at the Dollar Tree, and I ordered 10 succulent cuttings off of Amazon.
The key to picking a pumpkin, is picking one with a flat top. And then, you add hot glue and press down the moss.
Next, I added hot glue to the bottom of the succulents and pressed them into the moss. This small pumpkin took about ten little succulent cuttings.
I pulled off some of the bottom leaves of some of the succulent varieties. After you get it arranged, you can spritz it with some water about once a week. I've read that the succulents can take root, but regardless, these should last awhile b/c succulents are pretty forgiving. When I'm ready to move from fall to Christmas decor, I'll probably try to slice off the top of the pumpkin where these lives and place it in a flowerpot and see what happens.