Cheesehead is usually a derogatory term that refers to a person from Wisconsin or the Netherlands (it may also be used by natives of the region in a non-derogatory fashion), referring to the large volume of cheese production in those locales.
Cheesehead is also the name of a brand of hat that is shaped like a large wedge of cheese (generally made out of some light plastic). They are primarily worn in Wisconsin, generally at the football games of the Green Bay Packers. Green Bay Packers fans wearing these hats are called Cheeseheads.
The 'Cheesehead' trademark is owned by Foamation Inc. of St. Francis, WI, who began manufacture of the wearable, foam cheesehead in 1987.
