These are extremely difficult and only a few have been found.
Devore Authentic sold for $1659 -
auction
Sheckard PSA 1 sold for $3850
auction
Tannehill PSA 2 sold for $4150
auction
A steal here, McGraw and Gandil in a lot for 5k
auction
There were another three of four hidden in REA lots.
I used to own a Duffy.