Here is some mustard I grew one year. I started it from seed in our front garden bed in the late summer. I ate most of it, because my other family members were not stoked on its spicy taste.
When I could eat no more I let it flower. By now it was springtime. The white butterflies (cabbage moths) and other flying creatures loved the nectar that the flowers provided. They flocked to our yard and were really lovely flying all around. When it went to seed I collected the seeds in brown paper bags. When fall came around again I used the saved mustard seeds in my homemade pickles.