I always run a Google search on a new name that I am researching, but I rarely run it as the first step in the search. This time, though, I vaguely recognized Thomas Masters White from earlier research in that same county. And while the surname "White" alone would undoubtedly yield hits in the millions, the middle name was just different enough that a search on the forename, middle name, surname combination might turn up a hit on on my man.
Sometimes it is better to be lucky than to be good. My search found four hits. Two were queries that led nowhere, and one was a pedigree for his first wife's family that listed the marriage. The fourth was the Treasure Chest - or at least the key to the chest. It was a State Archives catalog entry for a collection of personal and business papers from 5 intermarried families that in the end had been inherited by one single woman who ultimately contributed them to the State Archives.
There were 23 cubic feet of records: family bibles, literally hundreds of letters, photographs, legal and business documents, wills, guardianship papers, deeds, store receipts and many, many others. And while some of the individual records, such as the wills would have been found by my standard searches iin the county records where the family lived, none of the personal correspondence or photos would have been.
The records began around 1800 and continued until well after the the turn of the next century. It was a sizeable slice of history collected and stored in 39 boxes. It took a very long time to go through, but I was smiling nearly all of the time.
I have since found other collections of private papers. None has held as much relevant family history, but some have mentioned ancestors and several have shed light on how my ancestors lived. I heartily recommend looking for them in your research area. Major repositories such as State Archives, large libraries - and especially university libraries are the most likely place to find them.