The 1955 work is valued at $1,000 (£734). The 1897 Biscuits Lefevre-Utile poster on the right, showing a girl in a dress made out of sickles and wheat, was designed to show the origin of their snacks. The biscuit brand still exists today, though it has been running under the US company Mondelez International - which also owns Cadbury and Oreo - in recent yea...