First, a scan of Rita Hayworth on the cover of the March 1943 issue of Modern Screen magazine, made to look like an actual Valentine card.
The "magazine as a Valentine" was something that the fan magazines did fairly often from the 1930s through the 1950s. Modern Screen was especially fond of doing it. Unfortunately this is the only Valentine-themed magazine that I own, but hopefully I'll come into possession of more in the future!
Joan Leslie as the Queen of Hearts in the 1940s.
Adorable Puerto Rican actress Olga San Juan in 1945.
Nancy Carroll in the 1930s.
Lana Turner posing in front of a giant red velvet heart, 1940s.
Betty Grable's leggy Valentine's Day photos are still very popular. Here's a slightly less common one, from the 1940s.