Leon -
Nice grab! I have the same New Haven Colonials PC as yours (one of the few known examples).
I'll try not to hijack this thread with all the pre-rookie HOF RPPC's in my collection...but here's one that I've only shown once before, so it might be new to a few folks. Also, along the same lines, it's a postcard of a baseball HOF executive really early in his career.
Warren Giles - coach of the 1918 Moline HS Basketball Team:
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http://imageevent.com/derekgranger
HOF "Earliest" Collection (Ideal - Indiv): 244/342 (71.4%)
1914 T330-2 Piedmont Art Stamps......: 114/119 (95.8%)
1923 V100 Willard's Chocolate............: 177/180 (98.3%)