The walking mills resembled fat metal serpents, rather larger than those Chinese paper dragons animated by files of men in procession. Sensory robot devices in their noses informed them that the waiting wheat had reached ripe perfection.

As they advanced, their heads swung lazily from side to side, very much like snakes, gobbling the yellow grain. In their throats, it was threshed, the chaff bundled and burped aside for pickup by the crawl trucks of a chemical corporation, the kernels quick-dried and blown along into the mighty chests of the machines. There the tireless mills ground the kernels to flour, which was instantly sifted, the bran packaged and dropped like the chaff for pickup.

(Walking Mill from Bread Overhead!)

A cluster of tanks which gave the metal serpents a decidedly humpbacked appearance added water, shortening, salt and other ingredients... The dough was at the same time with gas...