Let me tell you about it.
One of the reasons I feel so fortunate in my practice as a historian, such as it is, is that I have a significant background in literature. Believe it or not, literature really helps to fill in the gaps in the historical record, particularly things like realistic novels, comedies of manners, and social satires. More often than not, works of fiction like these have accurate (confirmably from the evidence) descriptions of the popular culture at the time they were written.
As much as young fogies like me (if I weren't a democratic socialist, I'd definitely be the kind of person who gripes about the "good old days," and how bad the good old days really were) would like to ignore it (*coughBritneySpearsMarkWahlbergandTimeMagazinecough*), the sad fact of the matter is, popular culture goes a long way towards explaining history.
And there's the flaw. We know a fair bit about what a lot of ancient cultures thought was important, but we know very little about the day-to-day lives of ordinary people in those cultures. It's pretty easy to figure out what the kings and emperors, princes and princesses and potentates were doing, but it's harder to figure out what the common person was doing (and about tenfold if the common person in question was a female common person).
This is what's so interesting about historical archives like The Crypt of Civilization, which contains among its relatively useless items some actually interesting things, like "1 package Butterick dress patterns," various toys and household items, and numerous samples of synthetic products that aren't, as far as I can tell, even made anymore (a mere 67 years later). Because it's accessible, the Prelinger Archive at Archive.org is even more interesting.
Both of these collections house significant amounts of ephemera -- stuff that appears and vanishes quickly, and isn't generally kept, things like dress patterns and printed advertisements and television commercials.
With that in mind, I'd like to make a few suggestions. If anyone reading this is ever planning on building a time capsule, here are some things you should be thinking about putting in:
- maps (yes, they go out of date quickly; that's the point!)
- transit and train schedules
- general-interest magazines and similar media (a copy of TV Guide!!)
- television commercials
- an ATM receipt
- posters, flyers, and other promotional items, particularly political ones
- articles of clothing
- faddish products of the time
With any luck, future archaeologists and historians will have a fairly easy time documenting this era, but it never hurts to want to give them some help.