My family and I went to Sever's Corn Maze and Fall Festival close to Minneapolis, MN around Halloween. Each year a different maze is constructed out of corn and it is large enough to walk around in for at least an hour or two. There is also a different "challenge" each year- finding different letters or pictures hidden throughout the maze, for example. My siblings and I had fun running through the maze trying to complete it as soon as possible, but it still took us a while!
In addition to the maze, there is a large petting zoo and some small shows of different sorts. There is also food available for purchase. Most is typical of "fair food", but there are also some very Midwest options like brats and cheese curds!