A number of coins were issued for the 76 Olympics. Without knowing which one, and condition, it's impossible to give a value.
What country? The US did not issue any Olympic stamps in 1948. its in great Britain
That will require a more detailed identification to figure out what the value is. Consult a postage stamp catalog, Scotts is a standard in the US. It should be available in your local library. It will help you determine the specific stamp and provide a value for you.
Barely, probably the face value of the stamp.
The D stamp has a face value of 22 cents and can be used on domestic mail at that value.
15 cents.
Forever
value is 25 cents
The F series stamps were issued in 1991. The postage stamp has a face value of 29 cents.
The current value for a standard postage stamp is 46 cents.
The value of US commemorative stamps varies depending on type and issue guide. They can range anywhere from a minimal value for a used stamp to thousands of dollars for a rare mint condition stamp. There are many US stamp price guides that can be obtained to find out a catalog value. Stamps in the US that are unused can always be used for face value as postage.
4 cents
The F series stamps were issued in 1991. The postage stamp has a face value of 29 cents.