I bought my son the SillyYak shirts!!! He loves them. I bought 2 kinds from 2 different places on cafepress, one had the definition of CD on the back which I have him wear on the first day of school.
I also bought him a button, "don't poison me" with no gluten info on it.
He was 3 1/2 at dx and now 4 1/2 - I feel better if he can point and have some way of communicating other than him saying "it's got guttons?" maybe his former "it's gots wheats?" was better...