Sandpaper match striker cards are a category I like, this one from a "shoeist".
Lions rampant, European heraldic and royal symbology since the 12th century, used to promote Midwestern flour.
An unusual CDV portrait of a Doctor Galen E. Bishop of St. Joesph, Missouri, with lengthy text on the back disputing what he saw as widespread rumors that he was dead and/or always drunk and/or incompetent. He urges patients to visit him, and see for themselves how sober he is. And his photograph stands as proof that he is still alive.
The text on the back of this stock card gives proof of the barter system being still alive and well at the time: this merchant gives notice that he will take maple sugar in exchange for his products.