There's no expiration date on this coupon, but since it's from the turn of the last century I don't suppose you could count on getting a cookbook. You could try. Don't forget to send ten cents in cash or stamps!
In 1878, the Washburn 'A' Mill was the site of a famous explosion caused by the ignition of flour dust in the air. The explosion flattened the mill and surrounding area and killed 18 people. The incident led to reforms in the milling industry.
Washburn-Crosby Millers, the makers of Gold Medal Flour eventually merged with other smaller mills to become General Mills.