Here is a very interesting cereal premium with coins from the late 1950’s or early 1960’s. It is still sealed in its original shipping envelope! The address has no zip code, so it was mailed before 1965. It is the Wheaties Mystery Coin Collection. You could get one of these fantastic 15 Foreign coin sets by sending one Wheaties box top and 25 cents to Wheaties Foreign Coins in Minneapolis, Minnesota.
While these sets are not particularly scarce, I have not found any others that were still sealed in their original mailers. So this set is as pristine as can be – still unopened after more than half a century! (The pictures of the card and coins was taken from another set.)