A warehouse receipt is a receipt issued by a storage facility describing and acknowledging receipt and possesion of the goods that are being stored by the facility.  If the receipt is negotiable, the facility will release the goods only to the person named in the warehouse receipt (e.g. the bank that has made the loan to the farmer) or someone to whom the warehouse receipt has been properly endorsed.  In Article 9 terminology, a warehouse receipt is one form of "document."  See U.C.C. 9-102(a)(30) and U.C.C. 1-201(15).