In my family, gifts were not given at graduation. But there was one gift I received that corresponded to a graduation, and is useful to this day (coming up on 40 years, this August). I graduated junior high school and turned 13. In my family, as I chose, that meant a bar mitzvah, a coming of age ceremony with study and public reading at a synagogue. I got a gift then - a Webster's 3rd International Unabridged Dictionary. It is old and the spine is broken. It is heavy. And, 40 years later, I am the writer I wanted to be when I was 13, and a skilled writer who does research. And it all started there.
If I were to give a graduation gift now, it would be a book, or a gift of words.