I've been pretty lucky that my local Wal-mart carries gluten-free Rice, Honey Nut, Corn and Cinnamon Chex. BUT...I had an experience of my own with that.
I bought a box of Honey Nut Chex that had the gluten-free designation on the front. Ate half the box, no problem. Had a bowl one morning, prepared as I always do with fruit on the top and the same brand and type of milk as usual. As I was eating, I noticed 2 slightly smaller and darker appearing Chex in the bowl. It brought me up short and I hemmed and hawed around about eating them and/or finishing the bowl. Eventually, I figured th