Some of the things to be found on eBay are amazing. A few years ago I was
very fortunate to be the high bidder if a 78 rpm (lateral cut inside start)
shellac of a 'greetings' address that FDR made via telephone to people
present at an event of the NYC PBA (New York City Patrolmans' Benevolent
Association) in February, 1936. A few weeks ago I described the disk to
Matthew Hanson of the FDR Presidential Library. He informed me that they
knew about the event but hadn't known that a recording had been made.
Being a shellac, it's reasonable to assume that others were made and
survived. Perhaps it's unique, perhaps not. I've posted the audio & a
dressed -up scan of the label so that any of you who are interested can
hear and view the files.