Whenever I see one of these 60s era Valentines, it takes me right back to Maywood Hills Elementary School and the crepe paper decorated boxes we always made for our class Valentines. And going to Sidies or Merediths to buy the box of cards, punching them out (and you always had to cut out and glue the envelopes together, a real pain), and addressing them to your classmates.
I suspect that in those less kind days, we did not have to give cards to everyone in the class. And left out the kids we didn't like. I apologize 50 years later if I snubbed you.