Haggis is a savoury pudding containing sheep's pluck (heart, liver and lungs); minced with onion, oatmeal, suet, spices, and salt, mixed with stock, traditionally encased in the animal's stomach though now often in an artificial casing instead.s haggis cannot be exported to the United States, it is instead made there, sometimes by Scottish companies. One such uses what is stated to be the same 150-year-old recipe and ingredients as in Scotland, except that sheep lung is not used, and the casing is always artificial.