I was admiring this list of cool artifacts, thinking I had none, then remembered in the corner I have a 64K PDP11 core plane, which, when it failed, had a V6 kernel image in it.
Now, that was 50 years ago, so magnetic donuts or no, that image is long gone, but it's still fun to think about.
Also, I have a DECTape from the late Jim McKie, somewhere, but I forget what was on it.
I still have my "documents for use with ..." book, and the BSTJ, but so do many of you ;-)
Finally, somewhere, I also have a budget page from a document I found in a dumpster at Murray Hill. This would have been 2007, or so, when lots of people were leaving and lots of offices were being "dumpster lobotomized"; I saw the doc in a dumpster and ripped out that page. It seemed of interest.