The OP indicated that the gift was NOT going to be one related to a charitable contribution-------- however, the recordkeeping should be nearly the same for either case.

Personal gift

Make sure the circumstances of the gift show that the transferor is releasing ownership entirely.......that the valuation is based on xyz references.....and that, in this case, the quantity is verifiable.

Having the elevator (whomever is holding the grain) show the transfer in their records, including the responsibilities for storage, to the name of XYZ.......would prove transferee, prove giving up ownership, prove quantity, and keeping a record of that day's markets would then, taken together, prove the amount and existence of a bona fide gift.

Charitable donation

With respect to a charitable party, such as a church------ circumstances are the really the same, but I would GUESS that the form (number escapes me right now) that must be attached when donating property, should be attached to show that a substantial gift of physical product was given, and the circumstances related to the gift were adhered to according to the rules related to gifts of property------ even though no actual deduction would appear in the tax return.

Be advised------ I have never had this issue of giving inventory to charitable organization, so the procedural elements might be different than I stated immediately above......but just bear in mind the objectives-------- the only difference is that you would not be taking a deduction within the return, ie a numerical amount, but you are still performing the act of charitable giving.....so the rules related to verification would most likely apply.