I have figured out some sources of resistant starch because I have to avoid it - sets off attacks of proctalgia fugax (which is more painful than either a heart attack or a blocked gallbladder, from personal comparison). The only thorough survey of its occurrence in foods that I know of is an article about 20 years ago in the European Journal of Clinical Nutrition, which is impossibly difficult to get hold of. Meanwhile: unripe bananas are really bad news.