I can think of 2 TV episodes which included stamps.
"Family Affair" was a sitcom of the late 1960's starring Brian Keith. His character adopts his nephew and nieces after their parents are killed in an auto wreck.
The episode is called "Stamp of Approval." Here is a synopsis of that episode:
Bill and Jody try to get on the good side of female friends in order to get something they want. Bill wants to land a construction contract with her foundation, and Jody wants a stamp for his collection.
https://www.imdb.com/title/tt0576784/"The Odd Couple" was a TV sitcom of the early 1970s based on the Neil Simon play and film, starring Jack Klugman and Tony Randall.
Stamps were a key theme for the episode "The Big Brothers." Here is the synopsis:
Oscar and Felix join the Big Brothers foundation. Felix tries to show his little brother culture, but he prefers to be with Oscar.
https://www.imdb.com/title/tt0664277/There are several scenes where Felix shows his stamp collection to the "little brother," and the Zion Canyon commemorative of 1934 gets special attention when the stamp appears to be missing from Felix's collection.
Felix asks Oscar, "Oscar, what happened to Zion Canyon?"
To which Oscar replies, "Umm.... oh yeah he couldn't hit a curve call so they sent him down to the minors."