Going through my late mother's stuff and found this sheet of unused stamps "The World of Dinosaurs" from 1997. She liked to collect stamps and she was a smart lady, but there are 2 things I don't understand. First, she or someone affixed the entire sheet to the blank envelope it came in. Second, the stamps have been hand cancelled. (She used to live in Grand Junction but long before she got these stamps.) So they're unused... but cancelled.
Is this a thing in the world of stamp collecting, or was it just a whim of hers? I don't get it.