Although rice is not one of the standard grains (such as wheat and barley), Halacha nevertheless treats it as a grain because of its resemblance to standard grain, and thus it requires the Beracha of "Mezonot." Therefore, one recites "Mezonot" before eating cooked rice or products made from rice flour, though the Beracha Aharona recited after eating rice products is "Boreh Nefashot," and not "Al Ha’mihya."
This exception is made only for rice. Products made from other types of unconventional flour, however, are not treated like products made from wheat flour, and so the Beracha is "She’ha’kol." A common example is corn flour, which is made by grinding corn, and then used to make different kinds of products. Such products require "She’ha’kol," even though the corn flour is being used in a manner similar to standard flour. The same applies to flour made from millet, soybeans, quinoa, or other grains. These are not treated like wheat flour or rice flour, and the Beracha over products made from such flour is "She’ha’kol."
It should be noted that some people make the mistake of thinking that corn muffins are made from corn flour, such that they require the Beracha of "She’ha’kol." This is incorrect. Corn muffins are usually made from ordinary wheat flour, but have corn flavoring – just like blueberry muffins are made from ordinary flour, and blueberries are added for flavor. Therefore, the Beracha over corn muffins is "Mezonot," just like over ordinary muffins.
Summary: Although rice flour is treated like ordinary wheat flour in that it requires the Beracha of "Mezonot," other types of unconventional flour – such as corn flour, or flour made from millet, soybeans or quinoa – are not treated like ordinary wheat flour. Therefore, products made from such flour require "She’ha’kol." One should be aware that corn muffins are made from ordinary wheat flour, with corn added for flavoring, and so the Beracha over corn muffins is "Mezonot."