Factual error: Charlie's 58 Impala is a sweet ride, but his license plates don't have the requisite year stickers. His car has the '56 series of plates, and each subsequent year would require that current year's sticker.
Factual error: Her dad buys a brand new Ford Edsel. In this scene, her mom is reading the invoice window sticker. The movie takes place in the fall of 1960. The car is actually a 1958 model.
Factual error: In the scene in Bodell's Music Store, there is a copy of Al Martino's Spanish Eyes LP in the rack. It didn't come out until 1966. Also, You Can't Sit Down by the Phil Upchurch Combo was not a hit until June 1961.
Answer: She was selling jewelry because the Edsel was a purchase they couldn't afford. She didn't want Peggy or her husband to know. The same reason they eat creamed chipped beef on toast and rutabagas - cheap food. The hat business was not doing well in 1960. Fewer men were buying and wearing hats by then.