Top: Collectible button from Strahorn Hutton Evans Commission company. Most stockyards memorabilia of interest to collectors predates 1940. The rarest pieces date as far back as the 1870s. From the collection of Mitchell McKay. Right: Gene Salmans, a buyer at the St. Joseph, Mo., stockyards, collects memorabilia like the tins shown behind him. Stockyards items are numerous, but some are difficult to obtain, and their values are increasing.