Here's an example of a restaurant that serves "mutton" when in reality it's lamb

"It is close to impossible to even find mutton in the U.S.," says Ken Albala, professor of history at California's University of the Pacific. "It costs more to raise sheep for longer periods of time, and the decline in wool production in the U.S. is directly related to the decline in mutton as a culinary delicacy."

Millennials and more experimental diners on both coasts might be open to eating mutton, McGuire says, but when one high-end restaurant in New York City purchased her USDA-inspected mutton, it "cost a bloody fortune to ship — three times the cost of other meat." Mutton must be shipped overnight and packed in dry ice, and the additional costs, McGuire explains, include a Hazmat charge on top of an overnight shipping charge.