Hamburger Cheese (usually processed cheese slices but often Cheddar, Swiss, pepper jack, or blue), either melted directly on the meat patty or crumbled on top, is generally an option. Condiments might be added to a hamburger or may be offered separately on the side including mustard, mayonnaise, ketchup, salad dressings and barbecue sauce. Other toppings can include bacon, avocado or guacamole, sliced sautéed mushrooms, cheese sauce, chili (usually without beans), fried egg, scrambled egg, feta cheese, blue cheese, salsa, pineapple, jalapeños and other kinds of chili peppers, anchovies, slices of ham or bologna, pastrami or teriyaki-seasoned beef, tartar sauce, french fries,
Hamburger critics like Josh Ozersky, a food editor for "New York Magazine", claim that this sandwich was not a hamburger because the bread was toasted. One of the earliest claims comes from Charlie Nagreen, who in 1885 sold a meatball between two slices of bread at the Seymour Fair now sometimes called the Outagamie County Fair. The Seymour Community Historical Society of Seymour, Wisconsin, credits Nagreen, now known as "Hamburger Charlie", with the invention. Nagreen was fifteen when he was reportedly selling pork sandwiches at the 1885 Seymour Fair, made so customers could eat while walking. The Historical Society explains that