Mustard plants produce three types of mustard seeds (arguably two): Yellow and brown. There are other varieties, like black mustard seeds and even white mustard seeds, but they are variations of yellow and brown.Here's how each plays out:1  Yellow mustard seeds: These are the most mellow (and often just get mixed in with white). 2  You can find them in our everything bagel mustard for texture.he Three Types of Mustard Seeds March 31 2014. Grab your pen and paper. It's time for Mustard 101. Today, I'm going to walk you through where mustard comes from. It's a rather simple process, but the blank canvas provides a ton of creative opportunities for wild flavors of mustard.