Annual plant, known as brown mustard or black mustard. Mustard seed sprouts can make a flavorful addition to salads. Simply let them germinate in any humid environment, and you can eat the resulting sprouts. And of course, brassica nigra seeds are one of a few different types of seed used to prepare the condiment, mustard. The seeds can be ground into a poultice to be applied externally for rheumatism and various other aches. Black mustard seeds reportedly work well in baths too. The seeds have stimulant properties, and can be applied to the skin to promote circulation and help heal bruises.