BILL CRIDER'S POP CULTURE MAGAZINE
I certainly remember that one specifically, from early/mid '70s comics. Rival: Olympic Greeting Cards, based as I was in Enfield, CT, just before Lego came to snap and build in that small city.
Selling those seeds was my first job! I never got any of the prizes as I elected to go with the cash option which was always spent on baseball cards and more comic books with that ad on that back.