Buckwheat is not a grain technically, but it can be used in same way: as a gluten-free flour or in hot cereal and side dishes, like rice.
Buckwheat is sold whole-groat, raw or roasted, crushed roasted groat coarse and fine, and milled into flour. Whole and crushed buckwheat groats are boiled in water. Two part of buckwheat to three parts of water is a good ratio, one to one works as well. Buckwheat flour can be used instead of part of the wheat flour in bread, pancakes, cupcakes, and crepes. It has no gluten and doesn't rise as wheat flour, but it gets fermented by yeast. Buckwheat flour adds nutty taste, dark color, and somewhat dry and dense texture to bread and pastry.
I usually buy green raw buckwheat and toast it myself. I started roasting it first because my local store didn't have roasted buckwheat I was used to, but since when my children told me they like freshly roasted kasha (buckwheat hot cereal) better. To roast buckwheat, place it on a dry frying pan on a high to medium heat. Stir it often. As buckwheat roasts, it turns brown and smells like roasted nuts. It takes five to ten minutes to roast three cups of buckwheat on a 12" skillet . Put hot roasted buckwheat in a saucepan and add water so it's level is an inch above buckwheat's level. Bring to boil on high heat, reduce heat to medium and cook for another five to ten minutes. Les water makes more distinct, separate kernels, good for side dishes. More water makes buckwheat softer and mushier, good for hot cereal. Grit (crushed buckwheat, cream of buckwheat) is good for soft, comforting hot cereal and cooks faster. Note that buckwheat is not as thickening as cream of wheat or oats. A half of a cup of row or roasted buckwheat makes a reasonable serving for a kid's breakfast or a side dish. Cooked buckwheat can be reheated in a microwave, in a saucepan with added water, or on a frying pan with little butter or vegetable oil.
To serve buckwheat, add milk, yogurt, sour cream, or grated cheese. Whole-groat buckwheat is better savory than sweet. As a side dish or salad, buckwheat is served with chopped parsley, fried onion and/or mushrooms, fried ground meat, or sweet potato and pumpkin.
See also: kitchen, cooking rice, frying pan, hot cereal, bread flour, homemade bread.