Awkwardly, Jack watches his mother essentially beg the doctor to take some "homemade jarred fruit" as payment for his services (7.23). Guess the family really is poor.
Unfortunately, it's clear that the doctor's business operates on a cash-only basis.
After leaving the office, Jack's mom urges him to not be embarrassed by her request to barter. See, that's how the town used to run.
Jack isn't really down with this type of exchange system, and drums up some historical references in his head as proof: Captain Kidd wouldn't have paid his pirates in fish, and Alexander Graham Bell did not give away the telephone for free (7.32).
While Jack's mother values the old-style barter economy, she sure wishes she had cash to pay right now to get Jack's nose fixed.
When Jack asks if he can swap out a different punishment for being grounded, his mother tells him he can replant, tend and harvest some corn to feed the impoverished old folks.
Can't do it. Jack would be disobeying his dad, and he'd just have to mow it all down again.