while doing some cleaning I found 20 stamps like the Liberty Bell pictured in the top left hand corner on this page.
The USPS page says it is a first class stamp, but they were issued in 2007 when the FC stamps were either 39 or 41 cents.
if I put this stamp on a letter tomorrow, will it get returned (or arrive with postage due) because FC stamps are now 44 cents?
Or will the Liberty Bell stamp always be a FC Stamp no matter what the FC postage is?
On the page you link to, it’s described as a “forever stamp”. That means that it can always be used for whatever the basic rate is for a first class letter, so you can use it on a letter instead of a 44 cent stamp.
Looks like there have been more than one thread in the past about “Forever” stamps - here’s one. Ours are “Permanent”, yours are “Forever”. Different strokes for different folks I guess. 
The correct name for them is “get-rich-slow” stamps.
Step 1) Buy a million dollars worth of “forever” stamps
Step 2) Wait until postage doubles
Step 3) Resell stamps - PROFIT!!!
You apparently have some of the first Forever stamps issued. You’re up 60 cents.
According to this press release, almost all new first-class stamp issues will be the ‘forever’ type, so no more scrambling for penny stamps after an increase.
I’ve been wondering about this for a while, but for the ones that are not ‘forever’, is there any reason that the value is not just printed on the stamp? If I understand this correctly, the face-value of all the non-forever stamps will always remain the same, right?
I think normally, the USPS does print the value on all stamps. I think the only exceptions are when a rate hike is expected and they don’t know exactly what first-class postage will be, so that instead they print a letter instead of an amount.
We actually have some non “forever” stamps that don’t have either a postage amount or letter on them. They just say “First Class”, but they weren’t Forever stamps. They have an American flag on them. Very confusing.
Forever stamps are relatively new in the US. Previous postage rate hikes produced new first-class stamps with the denomination printed on them. Using them after a rate hike with no additional postage would cause them to be returned to sender for insufficient postage. It didn’t matter that they said “First Class” on them; that was just a gentle reminder of exactly what type of mail they were good for in their day.
But since the rates have increased on average every 2 years for the last 2 decades, people got sick of having to have 1- and 2- cent stamps so that they could use old stamps. Hence, the forever stamps: you buy them at the current rate, but can use them indefinitely. It also brings in a little short-term cash flow; if someone wants to lock in 44 cents for their postal price, they can buy thousands of forever stamps today, and still use them 1-per-letter for decades to come.
I’m confused: doesn’t the First Amendment require that stamps issued under federal law be non-denominational?
The USPS deals with that one by issuing stamps for Christian, Jewish and Muslim holidays. 
I don’t get why they don’t issue forever stamps here in Germany - it’s such an obviously useful thing to have, with no real downside to it for anybody (I guess the postal authorities are actually quite happy about people who buy lots of forever stamps now for use after a postage increase - what these people essentially do is give the postal service an interest-free loan for years).
I know German postal rates are quite stable - the last increase of the domestic rate for a standard letter was in 1997. In fact, as a result of the liberalization and the admission of private competitors on the market for postal services, rates are expected to drop rather than increase. Nonetheless, I think that the idea behind forever stamps is so obviosuly and intuitively appealing that I wonder why they haven’t introduced them here.
Speaking of Christmas… I have some stamps that are about 20-30 years old that just have Christmas Postage on them… no amount.
Here’s a web site I found …
http://www.knottywood-treasures.com/id39.html
I wonder if the post office has to pull letters that use these or even odd denominations to research and count up the total postage???