Portabella mushrooms are large, “meaty” mushrooms that are usually an earthy brown color. They contain vitamin D, copper, selenium, potassium, phosphorus, vitamin B6, and niacin. While there is some debate over whether the name is Portabella or Portobello, it is acceptable to use either spelling. Allegedly, the name arose from a marketing campaign in the 1980s to increase sales of large, common mushroom.