A fried brain sandwich is a sandwich of sliced calves' brains on sliced bread. thinly sliced fried slabs on white toast became widespread on menus 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 restaurants still offer them. they remain popular in the ohio river valley, where they are served heavily battered on hamburger buns. in evansville, indiana, they are still offered at several "mom and pop" eateries, and remain a favorite dish.

Source: Wikipedia