Yup, probably found grandma's stamps. Like I did. No value really, I checked and even checked if they would sell on ebay....when you figure in the cost of listing etc you don't even make what the face value of the stamps.
But the PO will still accept them on envelopes and packaging.
Now if there are any valuable ones on there I'd like to know, LOL,,,,I have a box full of them too, in sheets.
warm quilt hugs, sue