I have always loved the concept of time capsules. I have made a few in my day. One that I strategically buried in my backyard has remained hidden even to myself despite several attempts to find it! Maybe that's why I like sedimentary rocks so much: they are preserved remnants of a world gone by, our world as no human ever saw it but which is recorded in the composition, distribution, and geometry of sedimentary deposits.
This is why my interest is piqued by the Homeland project that is soliciting soil samplers across the U.S. to collect and send in soil that will be documented, put on display in the form of artwork, and then ironically buried as part of a time capsule, the purpose of which is probably something other than confusing future generations of geologists interpreting the paleosol (= paleo-soil) record. To be honest, I'm not sure why they are doing it, but check out their website to get a free kit of your own if you like!