Whole grains are a great source of fiber and energy, and some are even great vegetarian "complete proteins," (meaning they contain all 9 or 10 of the essential amino acids) just as meats, fish, and eggs are.
A number of them contain gluten though too, and as some of us have unfortunately discovered (bread can be so yummy!), our digestive systems simply aren't compatible with this protein.
So, when I had started a gluten-free diet, initially I had no clue what the heck I would be able to eat, since wheat and other 'gluteny' grains are so prevalent in foods. Nevertheless, with a bit of searching, I eventually found there are still plenty of good grains that I can eat without triggering GI problems.
Photos like the one posted on @eatlivepurefit's Instagram- can be handy as references. This one shows 10 grains that are either low in gluten or gluten-free!
Here's a list of a few
Gluten-free grains & flours: