There are many naturally gluten-free grains that you can enjoy in a variety of creative ways. Many of these grains can be found in your local grocery store, but some of the lesser-known grains may only be found in specialty or health food stores. It is not recommended to purchase grains from bulk bins because of the possibility for cross-contact with gluten.
The following grains and other starch-containing foods are naturally gluten-free:
Buckwheat groats (also known as kasha)
There has been some research that some naturally gluten-free grains may contain gluten from cross-contact with gluten-containing grains through harvesting and processing. If you are concerned about the safety of a grain, purchase only versions that are tested for the presence of gluten and contain less than 20 ppm.
Read more here from celiac.org, as well as the full version of this piece.