Indian mush was a term used in the 19th and early 20th century in American cooking for a maize porridge, effectively the same as a polenta. At the time, Indian meal was the term used for cornmeal, to distinguish it from other grains, all of which were called "corn" at that time (see Cornmeal, Dominant In Colonial Baking, Still Has Its Place, The New York Times, 1985).
A recipe from 1851 calls for handfuls of meal to be added to boiling water with a small portion of salt, and for the whole to be boiled for an hour, before being hung up to simmer for another hour, with four hours of boiling and simmering described as "not too long." It was eaten with sweet milk, buttermilk, or cream, or with butter and sugar, or with butter and molasses, or could be cooled, sliced, and fried much like polenta.