Letter to Beaver

"Leave it to beaver" (1957-1963) is an iconic American television situation comedy about an idealized American family of the 1950s and early 1960s. It stars Barbara Billingsley, Hugh Beaumont, Tony Dow and Jerry Mathers as the Beaver. - Wikipedia

In this episode, the letter Ward is holding can be read in freeze-frame:


From Shorpy via Laughing Squid