Hi, Leigh -
If you inherited the mineral interests there might not be a Deed. You may only need to research the County Probate Court Records in the County whoever you inherited the mineral interests lived at the time of their death. Perhaps the Official Public Records as well for any Affidavit(s) of Heirship on the Deceased.
If the mineral interests are in a different County than the County whoever you inherited from died in, then there should be a certified copy of the Probate Matter filed in the Official Public Records of the County the minerals are in.
Or, you could try asking the Landman that negotiated your Lease with you for a copy of whatever he has proving your ownership, whether it be a Probate Matter, Deed or Affidavit of Heirship. We refer to them as Source Documents (where your interests came down to you) and are usually happy to help with that sort of thing.
In the future, when you lease your interests add a Provision to the Lease where the Lessee (Company) has to provide you with copies of any Title Runsheets that they have prepared or obtain that cover your interests.
A Title Runsheet is a complete (sometimes limited) history on a given tract of land or interest. They can be quite expensive to have prepared - this way you get one for free.
Asking for maps of the properties won’t do you any harm, either.
Hope this helps -