While there is no evidence of Twain's endorsement of the Mark Twain Spring
Wheat Flour, I suspected that he might have had little or nothing to do with
it, as Lynn Richardson suggests. Since my last post, I was able to dig up a
Grand Rapids City Directory where the flour is advertised (without picture).
It was a 1937 directory, meaning that the flour was being produced nearly
three decades after Twain's death.