This is a ticket stub from The Beatles' 1966 Shea Stadium performance. Alas, I was not alive at the time, but my mom was a teenager (I'm giving her age away, sort of) and ended up going. Because she was a mega-Beatles fan, she held on to practically everything that had "The Beatles" printed on it, this ticket stub being one of them.
You'll also notice that she saved the mini-flyer-esque thing that you see in the picture. If you zoom in, you'll see it's a card detailing appropriate concert behavior as well as a few other odds and ends.
As far as I know, no one else has that particular item for sale (at least since I last checked). Feel free to message me with any questions. The item "BEATLES Original 1965 CONCERT TICKET STUB Shea Stadium, NYC" is in sale since Saturday, February 03, 2018.
This item is in the category "Entertainment Memorabilia\Music Memorabilia\Rock & Pop\Artists B\Beatles\Concert Memorabilia". The seller is "bsherosj" and is located in New Castle, Pennsylvania. This item can be shipped to United States.