American Agriculture First Act This bill requires the Agricultural Marketing Service (AMS) to purchase at least 75% of the agricultural commodities of the Food Purchase and Distribution Program from domestically owned enterprises if it is necessary to respond to trade damage from retaliation by foreign nations with respect to agricultural commodities. The requirement does not apply if the Department of Agriculture reports to Congress that meeting the requirement is not possible because the agricultural commodities available from domestically owned enterprises cannot meet the supply needs of the AMS; or would result in a greater than 150% increase between (1) the amount necessary to purchase the agricultural commodities, and (2) the average cost of the agricultural commodities purchased by the AMS in the prior 3 years. The authority provided by this bill expires on September 30, 2023.