Star Wars: The Last Jedi Trailer - 13 Easter Eggs & Secrets You Probably Missed
11. Journal Of The Whills & Jedi Order Logo
We see a small row of books in the trailer, as part of the Ahch-To sequence, and one of them we actually get to see opened.
Although it's not confirmed, it seems very likely that this is the fabled Journal of the Whills. In canon, it's an ancient journal that referenced the Jedi Order. In Legends (and it's not a stretch to imagine this being canon soon too) it served as a legendary record of events across the history of the galaxy, and was maintained by the Ancient Order of the Whills.
In Rogue One, Chirrut Imwe and Baze Malbus referred to themselves as the Guardians of the Whills, while the initial outline for the story that became Star Wars was called The Journal of the Whills, Part 1. The Journal was made canon by the novelisation of The Force Awakens.
On the page, meanwhile, we get to see the symbol of the Jedi Order, with the wings and shining light representing their role and beliefs. It appeared in The Clone Wars, but this appears to be the first time it's made it into live-action Star Wars.