Continuity mistake: When Peggy Sue passes out at her reunion, the first shot (from her perspective) is her on the floor, looking up at her daughter and Charlie standing about 6 feet away. The second shot is her daughter and Charlie crouching down close to Peggy Sue's face. In the third shot, Charlie is instantly standing 6 feet away again.
Continuity mistake: When Peggy arrives at the reunion she is greeted by a couple at the front door. Lighting screens are reflected on their lenses.
Continuity mistake: When Peggy Sue goes to bed after getting drunk, her mother tucks her in. First, you see her pulling on the bed's sheet only but when the camera angle changes, she is suddenly pulling on both the sheet and the bed cover.
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.