Button mushrooms are the most commonly used mushrooms in the world. They are small, about 3cm across, and grey in colour. They have a mild flavour and are great eaten cooked or raw. Nutrition: Button mushrooms contain many of the vitamins and minerals that are only otherwise found in red meat ? hence their reputation as being ‘meat for vegetarians’. Button mushrooms are very low in fat and sodium and are an excellent source of potassium making them great for your blood pressure and heart health. Storage: Button mushrooms should be kept in a paper bag in the fridge for up to a week. Ideal Use: Button mushrooms are great raw in salads or cooked as a side dish. They are great mixed in a casserole or other vegetable dishes and make great tasting gravy on top of a steak.