Polar Four Season Pieces and Stems Mushrooms are a great option for mushroom lovers who want the juiciness of fresh mushrooms without the short shelf life. Our mushrooms are cultivated in cool, dark growing conditions and carefully harvested by hand to ensure taste and quality. Mushrooms have been known to enhance your immune system in addition to being a low-calorie source of fiber, iron, zinc, vitamins, and essential amino acids. All Polar mushrooms are uniform in size and color, and firm in texture.