A long time ago in grammar school, we learned how to distinguish the four grains Oat (Avena), Barley, Rye, and Wheat: Oat is easiest to distinguish from the other three, as it just looks totally different. For the Pâtisserie, it's mainly used in cookies and then in the form of rolled oats or oatmeal.
Rye looks like a mix from barley and wheat: the corn ear looks similar to wheat, but in contrast to wheat, rye also has awns (however, much shorter than the barley awns). I use rye mainly for sour dough bread, but apparently, it's being used also to produce vodka, and also (again) for beer!
Wheat is probably the most often used baking grain, at least in Germany. As mentioned above, it has no noticeable awns!
It's probably common to all cereal grains that the rest of their stems is pressed and rolled into hay bales. As I've always wanted to know how that's one, I was delighted to watch a cute little red machine doing exactly that! I didn't see much, however, the machine drives around on the field and every once in a while, it drops a hay bale. But I still liked it ;-)
Apart from these cereal grains, around Munich there is Rapeseed, which we use for oil (or to drive our cars...), Potatoes and Maize (Corn) (another cereal grain and very very tiny still in this picture, that changed rapidly!).