Jennifer, McClain County has had quite a bit of Activity recently which is likely why you’re receiving letters.
You’re right to be cautious as there are many mineral buyers sending mass mail offers that can vary widely in price.
Platforms like EnergyNet and Oil & Gas Asset Clearinghouse can sometimes generate competitive bidding depending on the property and production history.
Another option is to have the minerals evaluated first so you understand their approximate value before deciding whether to sell directly or through auction.