Aren't there holes in those things? Scuse. I've only seen plow discs on the plow.
I suppose one could use anything. The Hopi use flat stones for baking their piki bread.
Mongolian stir fry is cooked on a 4' diameter steel disc. East Indians use the side of a
clay oven for baking their bread.
We use our wok for deep frying, stir frying and steaming. If that plow disc is deep
enough, it could be used for the same. Being able to deep fry and steam makes
for more options for your cooking, if it don't have no holes.