Story of Brussels Sprouts

Brussels sprouts, cauliflower, and broccoli are ultimately descended from wild forms of cabbage from the Mediterranean Sea region(1). That area is where the eating of cabbage sprouts is considered to come from. They would spread into Northern Europe in the early Middle Ages and the Brussels (modern-day Belgium) area later in the Middle Ages. It was in the Brussels area that Belgian cabbage would develop into the Brussels sprout(2).
Brussels would skyrocket in population with industrialization a few hundred years ago. Nearby Saint Gilles farmers had issues finding space to cultivate. The then-more refined Brussels sprouts grew in a vertical direction with heads tucked under the leaf stalks, so they required less land to grow. This made them a major blessing to the Brussels area(1). 
French settlers would bring Brussels sprouts to Louisiana as part of the eventually-global spread of the veggies. High nutrient value was a major factor of this spread(2).

References:
1. "Brussels sprouts, the Origin story." Nature & Garden, https://www.nature-and-garden.com/gardening/brussels-sprouts-history.html.
2. History Rob. "Brussel sprouts: history & origin." History Rob, https://historyrob.com/history-blog/brussel-sprouts-history-origin/.