Enclosing a solid object incurs a 20¢ 'non-machineable' surcharge. https://faq.usps.com/s/article/What-is-the-Non-Machinable-Surcharge-for-First-Class-Mail
They never make me pay extra for that when I send coins in an envelope. I usually just use an extra oz 20 cents if it’s over 1 oz.
Some postal clerks are sticklers for every rule. Others don't know or don't care. I prefer to print my own labels and avoid them altogether.
Stamps are basically worth their face value. Before I retired I had several male customers come in with notebooks full of old stamps, back to the 1920’s. They would use them for postage. Very neat and they paid nothing out of pocket.
I deal with a stamp guy buying stampless folded actual letters. He sends them to me with old stamps all the time. I save the envelopes he sends the stampless letters in.
Just about everything the USPS has issued since World War 2 is worth face value or less. About the only ones worth saving are the high denomination (dollars) from the 50s and 60s. But I find it interesting that someone was using stamps from the 1920s. Some of them can be quite valuable.
I used to be a stamp dealer, in fact, I still have some of my dealer stock. You guys are making me think about getting into it again. I'm near retirement age, maybe it will be a nice sideline. But I will never do approvals like I did 35 years ago. Too many rip-off artists out there. I didn't deal in US stuff much, it was mostly all foreign. But I'll ask you coin dealers out there: How did you start, and how do you buy coins wholesale? I note that one stamp wholesaler I used to do regular business with is still around...
So if "powered flight" was measured from the Wright Bros in 1903, that would put this stamp at about 1953 vintage. Cool.
I have bought stamps from dealers in the past and have received them with plate blocks for postage. Many times the post office does not cancell them. Don't know why.
Sometimes a machine can’t cancel or it misses a cancel. Then it’s up to a Clerk or the Carrier to cancel them and they just get too lazy to do so.
If they are really old ones (50s or earlier), they may not be phosphor tagged and the cancelling machines will miss them. The US didn't phosphor tag stamps until the early 1960s.
Quite a few stamp auction companies send out their catalogs covered with old postage. They get many mint sheets and plate blocks with collections which are basically only good for postage. A friend of mine regularly sells mint postage of odd denominations at 65% of face. The challenge is to get the proper amount of stamps on the letter. Remember time is money and most dealers I know would rather put three .22 cent stamps on a letter rather than dig around for the proper postage.
The dime made it "non-machinable" - there is a 20 cent surcharge for that. But back to using old stamps. In the past year, I have used 14 cent prexies [that's 1938 vintage] - catalog over a dollar, but no gum, so a hassle to sell. And I bought them well under face.
after me Da' passed away, i found his loose postage, stuff with very little collectible value, some from the 20's and 30's i used em all in 1 year mailing ebay packages, especially priority ones, some had 40 stamps on em, they must of hated me at the post office, they have to cancel all by hand, lol