Have you thought about Simplicity 5581? You can see it here:
http://www.simplicity.com/p-2252-boys-a ... s-hat.aspxIt is for boys and men. I haven't made it yet, so I don't know how easy or hard it is. It might be a little big for your little guy, the smallest size is for a chest of 22-23 inches. But you could make it with a larger seam allowance, if it looks like it would be too big.
I do know of the McCalls, Simplicity, and Butterick patterns, I absolutely detest McCall patterns. I avoid them whenever possible, as they have terrible instructions.