I've got some stamps

Hi I saved these stamps back from my great grandmother's estate. Some of them are postmarked, but I remember hearing somewhere (whether it is true or not I don't know) that some stamps are even accepted for sale with a postmark on them. Anyway, I collected these to possibly use in some art collages but I've been needing to save a lot of money lately to move to Portland, OR and work on getting an art business off the ground and hopefully making things a lot better and having enough money to donate to the peace corps until I get ready to join. Don't know if there are any "winners" here but am curious to know before I glue them next to a picture of a dead rat or something. I've got quite a few pictures so this will probably be a double posting if not a triple. I would appreciate any help and advice. Thanks a bunch, and take care. Emily.