While exotic ‘shrooms have been long touted for their health benefits, the most common (and affordable) variety of mushrooms in the US may pack the biggest health punch. White button mushrooms seem to promote immunity by increasing the activity of natural killer (NK) cells, which are a crucial part of the immune system, according to a study from Tufts University in Boston. For an easy health boost, toss raw mushroom slices into your next salad or sauté and add to egg or pasta dishes.