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For the most part, these stamps/letters are still worth just their face value - none are rare enough to have matured/increased in value. They can still be used - the USPS actually encourages this. I've rounded up a bit just to get this to a more 'auction-friendly' valuation.
An assembled philatelic collection, comprising:
(7) US Airmail 11 cent envelope
(10) Blue circle with 13 stars, 25 envelope
(2) Cherokee Strip United States Postage 6 cent
(8) United States 6 cent, Capitol Building
(2) United States Postage 5 cent, Magna Carta 1215 Yellow and Magenta
(5) Honoring U.S. Servicement Prisoners of War Missing and Killed in Action 6 cent
(2) Waterfowl Conservation 6 cent (Birds)
(4) Daniel Boone 1734 6 cent
(2) Register to Vote, Flag 5 cent
(5) Douglas MacAurther 5 cent
(2) The Amerian Legion 50 years, Eagle 6 cent
(4) 1 cent Andrew Jackson
(5) Stone Mountain Memorial 6 cent
(6) 50th anniversary US Airmail Service 10 cent
(1) The Land of the Free. The home of the Brave 15 cent
(1) Christmas Winter pastime lithograph by Nathaniel Currier 1855 13 cent
(1) Conserve wildlife, merlin national wildlife federation.
(7) Christmas 13c (Mailbox)
(10) 13 cent US Airmail (red)
(1) 10 cent United States We hold these truths.
(8) 11c airmail US (red)
*represents a fair-market value for auction purposes; retail or asking price may vary.
Please let us know if you have additional items to appraise, and thank you again for using Mearto.