California Code, Business and Professions Code - BPC § 17765

Any person who advertises the giving of trading stamps, or who gives trading stamps, with the sale of any merchandise or service, shall give those stamps, if the purchaser requests them, with the sale of all items of merchandise or service offered for sale at his or her place of business, unless that person advertises that he or she does not give trading stamps on certain items of merchandise or service and designates those items or services in the advertisement or posts a list of those items or services in a conspicuous place in his or her place of business.