Make him something. For my ex, I made him a mini bookshelf. It's a small box with 4 books in it. The spine of the books read: "History," "Naussica," "X-files," and "Friends". Books - because he loves books. History, because he loves history. Naussica, because that was the first anime film he'd watched with me and he hates anime and only watched it for me. X-Files cus at the time he was obsessed with it. Friends, because we watched Friends continuously for a while and had plenty of fun together.
Within each "book" was a little pull-out letter, with me thanking him and saying lovey-dovey things, and on one side would be a little picture that I'd drawn, illustrating one in-joke or a cute name that we called each other. On some of the pages I'd even created small 3D models of a sword etc (cus he likes swords).
On the box-shelf, I'd stuck a paper rose, and a card on the back writing "Happy One Year Anniversary!"
What did he get me?
He forgot.
But there you go.