You may even get them for free if you ask a farmer, or grocer, right AFTER Halloween. I was able to glean from two different farm fields last year!
I saw an interesting thing, as I was looking for pumpkins in good condition: one man was walking around with a hatchet and a bucket. He wasn't after the pumpkins; he wanted the seeds! It didn't matter if the pumpkin was shriveled or damaged; each pumpkin was chopped open and the seeds scooped out.
If you'd like to know how to turn that festive decoration into a form you can eat, it's simple. Basically, you clean it, cook it, and mash or puree it. I much prefer the flavor of fresh pumpkin to that from a can. It can be frozen for later use, dried and powdered, pressure-canned in chunks, or stored whole in a cool (55-70 degrees), dark, dry location. They can last the whole winter stored whole. I stored a Hubbard squash last November; I finally cut into it in July this summer. It was perfect.
For more detailed instructions for cooking it, along with a few dozen recipes, see The Great Pumpkin recipe book. To get cooking instructions and just a few of my favorite recipes-
Pumpkin Chili, Pumpkin-Pecan Yeast Bread, Pumpkin Muffins, and Pumpkin Pie-
see the Pumpkin Class Handout.