I am not sure of what type of cookie it is that you are looking for.

If your son can have other flour types, then here is a recipe that I came across and saved. I don't know who orginally had it. I just saved it in case I needed for the future. Here it is:
Brown Rice Cocolate Chip Cookies
2 cups cooked brown rice
1/4 cup arrowroot
1/3 cup honey
1/3 stewed dates or raisins
1/4 cup oil (grapeseed is pretty tasteless)
1/4 tsp sea salt
1/4 tsp cream of tartar
1/2 tsp baking soda

Put all in the food processor and whip well. When it looks like mush, add fake chocolate chips. These turn out to be a fairly chewy cookie that have almost a snack bar consistency. Bake at 300F for 1/2 hour and then let them sit in the oven for another half hour just to dry them out a bit more.