All of the envelopes will contain different items, but I think there's some hesitation from a lot of people if they don't have any reference point.  Most envelopes will likely have a postcard.  The black paper was something leftover from a project my wife was working on (http://arthropodsandpaper.blogspot.com/).  Some of the other envelopes have included a NYC subway pass, a booklet of Boeing products and small bugs similar to the dung beetles on that site, but more intricate.  I'm pretty sure every envelope will contain it's own unique set of items, so while this list gives you an idea, don't expect to receive any of the same items.

For the box, it was asked that it contain film photography themed items.  It shipped out with a polaroid camera, a 60s era Vivitar 110 camera with original carrying case and manual, and a small device for viewing film negatives.  All of the items were picked up specifically for this box from thrift stores and swap meets.  We were fairly certain the film negative viewer would work properly, based on being able to open it up and look inside.  The Vivitar camera looked like it had been very well taken care of and was still in the original hardbacked carrying case and had the original manual, so we figured there was a good chance it would work properly.  The Polaroid camera was more of a gamble, and might end up just sitting on a shelf.

I like to think of the boxes as a good way to get yourself a gift and still be surprised.