Hmm doing a little googling and from a Blowout Cards forum page they discuss the blank back and someone mention it was made by a milk association company Mid-Atlantic Milk Marketing Association (MAMMA). the version that has info on the back is genearally believed to be made in 1984, although there is something about it being 1986. Definitely something local to the Baltimore area. At least the original photo with Cal. There is some mention that it was part of a stadium giveaway. There is also some poster that uses the same photo.
https://www.blowoutforums.com/showthread.php?t=611260
Odd that only Cal's card number 105 is being found and no others from the set. What are we missing?
I collect: Baseball, Football, Hockey, Mostly Vintage pre1980, My Homie teams - Washington/Baltimore Teams Senators (Twins, Rangers), Expos/Nationals, Redskins, Capitals, Bullets/Wizards - HOFers - Non-sport (mostly TV shows and movies).
My Trade List is very much a work in progress
CaptKirk42s Trading Card Blog Curly W Cards Strive For '65 YouTube klandersen42