We used to regularly receive junk mail from estate agents, which took the form of a folded piece of paper, held closed with a circular red sticker pretending to be sealing wax. The piece of paper offers the recipient - who, frequently, does not actually own the house they're living in - the exciting opportunity to receive a "free market appraisal" of our home.
Presumably, the idea of these things is to fool people into thinking that normally, if you ask a real-estate agent to come and see what they reckon your house is worth with an eye to selling it, they charge you $500 just for picking up the phone. You can, of course, actually receive such a "market appraisal" for free.
One local estate agent has really raised the bar recently. We've received two of these things now:
That's a gold-embossed stamp in the bottom right corner of the "valuable Certificate" (it'd look better in a photo than this scan, but I can't be bothered). Note also the stock-certificate-esque border.
These "Certificates" remind me of the "surrender pass", a staple of the psychological-warfare business. Most air-dropped propaganda leaflets, along with saying that the dropping side had clearly already won, the drop-ees had been abandoned by their country, the Statue of Liberty is kaput, et cetera, also encouraged enemy soldiers to surrender and provided instructions on how to do so.
Some of the leaflets, however, went so far as to make one side into an actual "surrender coupon" or "safe conduct pass". Which kind of gave the impression that you weren't allowed to hang your undershirt on a stick and wave it at Allied soldiers unless you had the correct paperwork. Or that you could surrender without a pass, but might be in trouble afterwards if you lacked a This Man Not To Be Summarily Executed certificate.
(These things are of course still being printed; here's a big archive that extends to the first few years of the current Iraq and Afghanistan wars. This site has a lot of leaflets, too. There were also "black propaganda" leaflets, which pretend to be from someone other than the side that's actually dropping them. "Congratulations, comrades, on so courageously hurling yourselves upon the merciless bayonets of the enemy! By the time you are all dead, we will have conquered the world!")
A few propaganda leaflets had some sort of value. Some leaflets had valuable information on them, like for instance offering rewards to enemy soldiers who decided to help the other side. And a soldier who's trying to surrender may be a bit less likely to be shot if he's waving a yellow safe-conduct ticket in the air.
As far as any actual laws-of-war stuff goes, though, the standard air-dropped "surrender pass" was and is every bit as valuable as these junk-mail real-estate certificates.