I think most worldwide (and US) collectors recognize the US airmail postage stamp I’m writing today. In 1980 US post (along with Italian Post) issued a commemorative stamp to honor the 280th anniversary of Philip Mazzei’s birth.
The stamp exists in two different perforations: 11¼ and 10½x11¼ (latter having over 10x catalog value to normal stamp). In addition, this stamp has plenty of (easy-to-find) flyspeck varieties. They are nothing valuable or rare, but enough to catch the eye of casual stamp collector like me.
US 1980 Philip Mazzei 40c airmail postage stamp. Michel #1449 A (cat. value 0.40€) / Scott C98 - notice how the end of word "Airmail" floats separately in two latter stamps.
I also have found a pair where the airplane silhouette has an additional blue shadow caused by so called “kiss print”:
US 1980 Philip Mazzei 40c airmail postage stamp. Michel #1449 F(cat. value 5€) - Airplane silhouette with "shadow"
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