I mainly collect covers... Here's my covers with Black Jacks.
28C Prussian Closed Mail rate to Germany.
From Appleton, Wisconsin via the Detroit, Michigan exchange office with 24c Red Lilac:

From New York to Germany, same rate, with 24c Brown Lilac:

Double Rate cover to Lima Peru, British Mail via Panama with 24c Grey and 3c Rose:

With 15c Black (77) to Italy from Emmitsburg, Maryland 19c rate NGU closed Mail:

12c Treaty rate with 2x 5c Brown (76) to England, 1868:

2 singles with pair 3c Rose to Canada:
