Virtually any old book or item can contain genealogical clues. A person just has to look. A 1921 church cook book published in Warsaw, Hancock County, Illinois, contained numerous recipes from women in four north-central Iowa towns over two hundred miles away. There were over a dozen women from these Iowa towns who submitted recipes--with probably one "non-local" recipe on every few pages. Obviously there were several families who migrated to that region of Iowa from Warsaw, Illinois.
And if nothing else, the book documented residential information that may not have been available elsewhere.