Business & farm

Thank you.  The property is a (still) unimproved 10 acre lot in an unincorporated area.  We have been paying the taxes on the property since it was gifted.  How do we value the property at receipt?  We can refer to the tax records...would that figure be acceptable?  Could we use the last (current) tax value as the cost? We received only a personal check from the buyer for the agreed to price....no tax form(s).