Does anybody sell any non-book items at events?

Since I currently only have one book published, I am looking to possibly expand what I sell at my table at live events. Has anyone had any luck selling any other type of merchandise alongside their books?

Shirts? Hats? Tote bags? Trinkets? Do these things sell well, or no?

For example, here is a t-shirt idea I am playing with, but I don’t want to spend the money on a bunch of shirts if no one is going to buy a shirt about a book that they haven’t read yet.

All opinions welcome!