7 CFR §810.804

1. (a)U.S. Mixed Grain (grade). Mixed grain with not more than 15.0 percent of damaged kernels, and not more than 3.0 percent of heat-damaged kernels, and that otherwise does not meet the requirements for the grade U.S. Sample grade Mixed Grain.
2. (b)U.S. Sample grade Mixed Grain. Mixed grain that:
   1. (1)Does not meet the requirements for the grade U.S. Mixed Grain; or
   2. (2)Contains more than 16.0 percent moisture; or
   3. (3)Contains 8 or more stones that have an aggregate weight in excess of 0.2 percent of the sample weight, 2 or more pieces of glass, 3 or more Crotalaria seeds (Crotalaria spp.), 2 or more castor beans (Ricinus communis L.), 8 more cockleburs (Xanthium spp.) or similar seeds singly or in combination, 4 or more pieces of an unknown foreign substance(s) or a recognized harmful or toxic substance(s), 10 or more rodent pellets, bird droppings, or an equivalent quantity of other animal filth per 1,000 grams of mixed grain; or
   4. (4)Is musty, sour, or heating; or
   5. (5)Has any commercially objectionable foreign odor except smut or garlic; or
   6. (6)Is otherwise of distinctly low quality.