The picture shows a close view of this Old Celluloid Washburn Crosby Flour Advertising Pin Back Button. The printed yellow ribbon attached is also made of celluloid. It reads:
WASHBURN CROSBY CO. FLOUR WASHBURN'S TRADE MARK GOLD MEDAL EVENTUALLY WHY NOT NOW
It measures 2-1/8" and is in mint condition. It is not dated but believed to be from the 1920's - 1930's but could be older.