I thought those were baked acorn squash, but truth be told, that lower shelf is packed pretty close together and pretty close to the sides of the oven for proper heat circulation.
Acorn squash were halved and the seeds removed before being baked for the first half of the baking time facing down on the baking pan, then turned over, dabbed with butter then sprinkled with salt, pepper and some cinnamon. Microwaves really shorten the preparation time for these and baked potatoes, which were usually prepared along with meatloaf on cool fall evenings when it felt good to have the oven on.