Unfortunately this question doesn't seem to fall into any catagory on here so i'll post it here. For years now I have been donating used postage stamps to charities. I know what they use the funds from these stamps to buy but don't know what they actually do with the stamps.
I think they are sold on by weight but can't see what value they would have. I used to think they would go into packs of stamps for collectors but that doesn't seem likeley now. All I can think is that the actual stamp is made from a paper which is of high value.