I began collecting with largely history related autographs like Patrick Henry and presidents.  I have somewhere in my collection a large full-length portrait of Lou Henry Hoover if I recall it was inscribed to the wife of editor W. A. White.   I think Grace Coolidge is the only other First Lady I have in my collection.   You have a first-rate collection there.  I also love autographed letters signed to me the more handwriting the better.  Makes me shudder when people cut off inscriptions.