Technically, gluten does not exist even in wheat flour, it is produced. Two of the proteins in the starch in wheat flour, glutenin and gliadin, combine with water to form the complex known as gluten. When the proteins are surrounded by water and stretched, they begin to interact and form new bonds between each other, which are both very elastic and strong. When bread dough is kneaded, the protein molecules form elastic sheets of gluten, which trap the gasses given off by the yeast in the dough, causing it to rise.
Alan Davidson, author of The Oxford Companion to Food, says other grains including corn, rice, and barley do not contain the gluten-producing proteins, although they contain other proteins.
And we’re always eager to tell people when their questions are dumb, but yours is not. In fact, we came across a number of bread-making books that either imply or state that these other grains do contain gluten, although in insignificant quantities. But we’re sticking with Mr. Davidson’s answer.