Taking a stab at Joe's question of whether there might be much more historical information to be discovered about the early years 'in this country', I think only folks like Joe and other of our contributors (that I'm not going to try to go through the list to name and leave someone out) they are the best situated to try and answer from their experience of rummaging through the various archives. The only real first hand knowledge I have in any period historical research has been using our State Historical Society library, microfilm and such going back to H.S. and college years. But, I really have never done my own focused research on any historical golf related matters. So... my opinion isn't all that informed.
Yet, considering Peter's answer, I have a feeling that pretty much all the significant material has been unearthed. I think of it as 'what are the odds' that significant new information will be uncovered, given we are talking about an era of about 50-60 years, about a subject rather obscure and during that era, not a ubiquitous activity or sport followed or written about as widely. The significant material was observed and recorded in articles and books by a very small sample of writers in comparison to other subjects. So, the significant publications and likely sources where knowledgeable and expert observations and writings were published or recorded, are few and known to these old archive hounds. Maybe some obscure isolated and one-off publication or records may be unearthed in some old musty attic, but the odds that the material will be of truly 'expert value' written by a someone seriously experienced in aspects of the game of golf and its playing fields design, is slim that anything is left.
Enjoy those rare gems that folks like Joe may still unearth, but I am skeptical there is much left. And, be wary that any new material written by some casual observer without that era credential of recognized expertise of those times (like some local all purpose sports columnist) should be take with a grain of salt, anyway. IMHO.
Now, if you find the double secret confidential diary of some woman alleging to be the concubine of Dr. MacKenzie -or more shockingly Tom Bendelow
, - and who had written something told to her about GCA intent of a particular project.... then you might really have something!!!