(for the history of how I got here)
https://goscf.com/t/84680From a collection I got on
ebay: Final count in the box was 581. $34.68 (with tax and shipping} So ~6¢ ea. !!
Box was
all stamped envelopes.
Here are a few quick picks of ones I liked right away.
Going to the mountains for a few weeks. Taking the box (and the UPSS catalog) to work on all the varieties.

Will show more when I return.
Thanks,
pat
To USSR: Received PM on back.

FDC's are plentiful. Commercial uses seem harder to find (?) Received PM on back.

This one has some interesting details:
The basic envelope - One Cent Green on White, Die 161(B) U532a
3282 43 10 57 M-$100.00 U-$75.00. With PENALTY o/p price M=$35.00 Used not listed
As used by Harrison, Nebr. PO for C.O.D. notification (?).
With Harrison Nebr. Apr 30 1956 flag cancel.
Not listed in my Flag Cancel catalog. Only other example I found on
ebay was a cover from 1938.
https://www.ebay.com/itm/292704255455