Well. I was going to say salt, pepper and garlic. But then I read that salt is a mineral and garlic is botanically a vegetable. So I'll go with pepper, vanilla, and chile. Or maybe nutmeg.
Cinnamon, cardamom, and whatever they use to season Cajun/Creole foods (almost certainly a mix I guess).
I can't think of three. Other than pepper, the only thing I cook with spices is pumpkin pie. Store bought bakery items (like pumpkin and apple pies, bagels, raisin bread, cinnamon rolls, etc..) are so overloaded with cinnamon they taste bitter imo. There must be one spice in pizza sauce I'd miss more than the others. My mom's recipe called for oregano, so I'll add that. Black pepper, cinnamon (in moderation), and oregano.