There are many conflicting accounts in the story of who first invented the hamburger bun, so we will probably never know for certain. One version of the story credits a home cook from Oklahoma named Oscar Weber Billy, whose descendants claimed that their grandpa grilled up some hamburger patties in 1891 and put them on his wife’s homemade yeast buns (baked from her own secret recipe!); they were such a hit that Billy served them to large crowds of neighbors on the Fourth of July every year. Another version of the story gives credit for the hamburger bun to Walter Anderson, the cook behind White Castle, which began serving hamburgers on buns in Kansas around 1915. However, newspaper articles from 1908 and 1911 mention hamburger buns, and many people have insisted that hamburgers on buns were served at the 1904 St. Louis World Fair. So while White Castle may not have been the first place to serve hamburger buns, it is likely that the restaurant did help popularize them. Notably, there is no evidence that any of these early burger buns used sesame seeds. The earliest reference to a sesame seed encrusted hamburger bun found thus far appears in a 1955 Time magazine article about Bob’s Big Boy. However, in 1964, they were still rare, as the legendary New York Times critic Craig Claiborne cited their use as unusual in a review he wrote that year. While it’s not clear who was truly the first to invent hamburger buns or add sesame seeds to them, we do know who to credit for making the sesame seed hamburger bun as popular as it is today: McDonald’s. In 1968, the chain debuted the Big Mac, a double-decker hamburger served on a sesame seed bun. This helped solidify the sesame burger bun as the mark of a premium burger in the American consciousness and catapulted the now-ubiquitous sesame burger bun we all know and love into popularity all over the United States. (Notably, McDonald’s continued to serve most of its other burgers on plain buns and still does, while Burger King switched to using sesame buns for nearly all of their burgers.) Today, of course, the humble hamburger bun — with or without the sesame seeds — remains a key element in one of America’s most iconic foods and a beloved item all on its own as well.