Hope this ain't too off topic.
I too save all the stamp collecting related ephemera I come across. Little envelopes, pamphlets, guides, glassines etc..
As was mentioned earlier, approvals came in these little glassine envelopes. I remember getting them from H.E. Harris, if I remember right. Here is a selection of some of the ones I've accumulated over the years. they come from Mystic, Harris, Littleton, Jamestown, Kenmore, Garcelon and 1 unidentified on (in red).
I also remember getting stamps, in packages similar to this, at the local five and dime. They usually had a sortment attacked to cardboard, like these, with an additional glassine full, inside the package. this one is not old, I don't think, but you get the idea.
then there is little approval I rec'd in a collection a while back. I's a single Danish stamp (Scott #28), attached to a dealers approval "card", with a price. From the Globus Stamp Co. Not sure how old it is, but I'd guess 30's or 40's. Nice SON cancel as well.
Then there is this Russian (?) item I came across. I have no idea what it says, but I was told it is also something that would have accompanied a dealers packet of stamps.