Choose a small bean or seed. Nearly any type of bean can be sprouted, but small beans are generally the healthiest choice. Many large bean varieties are more likely to develop mold upon sitting in moist conditions for prolonged periods of time.
Mung beans are the most commonly used bean for sprouting.
Adzuki beans, lentils, alfalfa seeds, fenugreek seeds, and cabbage seeds are also fairly small and easy to work with.