It depends on a lot of different factors. In addition to knowing what country they are from, what year they are issued and the condition, you have to identify the specific stamp. A catalog on line or in you local library can help you figure out these and find a catalog value.
The Celebrate commemorative stamp, available as a Strip of 4 stamps, a Block of 10 stamps, or a Pane of 20 stamps. A sheet of 20 can be purchased for about $8
It is a Forever type Stamp so if available a local Post Office 0.45 cents. You can buy a minimum of 4 at USPS.com/store for $1.80 + shipping (.45 x 4). Stamp was introduced March 25, 2011.
Whatever the first class postage is
You can find 1978 Commemorative stamps of America on about.usps.com/who-we-are/postal-history/stamps-postcards.htm
what is the 1981 royal wedding commemorative crown worth
It may be purchased online from StampsForSale which has many commemorative stamps. You may also shop at RoyalMail which has a variety of gifts and stamps.
In general, they will have minimal value. You will need to more clearly identify the stamp to determine the value. There are a number of variations. Consult a stamp catalog to identify it.
I believe it is worth 150,000.
You can find books on Historic stamps of America 1978 Postal commemorative society on en.allexperts.com/q/Stamps-Philately-1610/2009/2/books-stamps-great-grandfather.htm
Face Value
$6.00
Nothing because while it is a commemorative medal it does not seem to commemorate anything.
These are five cent commemorative stamps. They are worth 20 cents used and 35 cents not used.
H. D. S. Haverbeck has written: 'The commemorative stamps of the British Commonwealth' -- subject- s -: Commemorative postage stamps
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