CHICAGO (AP) _ Grain futures were mixed Friday on the Chicago Board of Trade. Sept. corn fell by 0.25 cent…CHICAGO (AP) _ Grain futures were mixed Friday on the Chicago Board of Trade. Sept. corn fell by 0.25 cent at $4.39 a bushel. Sept. wheat was up 7.25 cents at $6.38 a bushel. Beef was mixed and pork was lower on the Chicago Mercantile Exchange.