Subsoil is a 1994 short story by Nicholson Baker that first appeared in the New Yorker magazine.
Nyle T. Milner is an agricultural historian writing a book on the harrow, a surface tilling tool which also harvests potatos without harming them. He stops at a motel on his way to a museum and finds an original Mr. Potato Head toy, which did not used to include a plastic potato, but instead had just the features to be placed in a real potato. The potato is old and unnerves Milner. After eating a leek-and-potato soup -- and noticing that no one else in the dining room is -- Milner also notices the motel's strange fascination with "fresh" potatoes. That night, he wakes up to find potatoes outside his room, moving towards him. He is attacked by the plastic features of the Mr. Potato Head doll, and passes out with potato sprouts planting themselves in his body. Milner wakes to find that he is a potato, being used with the plastic features by a child. Years in the future, another man finds him as a potato, shriveled in the same box, and the implication is that he will fall to the same fate.
The story is partially an allegory for the stress of overwork, and uses irony, Gothic elements, satire, and the power of nature as its major elements.