My hunt to find other Cowan's baseball items to compliment the box hasn't turned up any cards (Leon, you told me that this would be highly unlikely, and I belieive you!), but it has turned up a small tin, candy bar mold, that highlights a early 1900's baseball figure ( I assume, from the cap and style of pant) in mid-swing.
Thought I would share for those interested.
It measures 3.5 " x 2 ". Can't find any mention of this product ("The Winner") either. chris