The movie has Lou Jean almost obsessed with Gold Stamps so I had to go look it up:

Trading stamps are small paper coupons given to customers by merchants in loyalty marketing programs that predate the modern loyalty card. Like the similarly-issued retailer coupons, these stamps only had a minimal cash value of a few mils (hundredths of a cent) individually, but when a customer accumulated a number of them, they could be exchanged with the trading stamp company (usually a third-party issuer of the stamps) for premiums, such as toys, personal items, housewares, furniture and appliances.

(source)