Fried-brain sandwiches generally feature sliced calves' brains on sliced bread. Thinly sliced fried slabs on white toast became a ubiquitous menu item in St. Louis, Missouri, after the rise of the city's stockyards in the late 1880s, although demand there has so dwindled that only a handful of eateries still offer them. But they remain popular in the Ohio River valley, where they are served heavily battered on hamburger buns .