Leasing Activity in Garvin - Section 3, Township 4N, 1E

My family has had mineral interests in Panola County since the early 1940's. And over the course of that time have received unsolicited offers to purchase their interests which were ignored. Recently the offers have been increasing in both frequency and dollar amount. With tax appraisal valuations at the lowest I have ever seen, what is the draw to purchase the properties at the highest offers?