1. Meat and Poultry
The importation of any form of meat or poultry products is banned and frowned upon by the US Customs. They allow the importation of canned meat that is neither goat nor lamb from countries where there is no case of Mad Cow Disease.
Whether if the meat or poultry product is canned or not, it is prohibited from countries like Canada where there is a presence of Mad Cow Disease. You can import pork from Mexico as long as it is in small quantities and is for instant consumption with a meal.