According to McSween’s website, their haggis contains:

Oats, Water, Vegetable Margarine (Palm Oil, Rapeseed Oil, Water, Salt, Emulsifier (E471), Flavouring), Black Kidney Beans (10%), Carrot (5%), Swede (5%), Mushrooms, Red Split Lentils (5%), Rehydrated Onions, Pumpkin Seeds, Sunflower Seeds, Salt, Ground Spices.