Oatmeal

Oats supply starch for energy along with soluble fibre, mainly beta-glucan, and they have more protein and fat than most grains. They’re whole grain, and they’re not often named as an allergen in pets.

Foods labeled grain-free won’t include them. Whether grain-free helps a healthy pet at all is a separate question: grains are a common source of allergy concern, but the review evidence points to meat and dairy more often.