The listing, 5th and 6th international philatelic exhibition memorabilia 3 pcs has ended.
So i dont know a whole lot about stamps, and i dont know what these are worth. But they are souvenirs, preserved beautifully in mint condition in official stamp exhibit protective sleeve. There are 3 pcs here, the 3 and 8¢ stamp piece is from the 5th International Philatelic Exhibition in New York, NY, 1956. There are two identical 5¢ pieces from the 6th international philatelic exhibition, Washington DC, 1966.