A starch is a certain type of carb - a subcategory, if you will. You have your sugars, you have your fiber, and you have starches. If you look on a nutrition label, add up the sugars and fiber, and subtract that from the total carbs, the remainder should be the amount of starch.
I would recommend taking digestive enzymes with meals that contain starches as a temporary measure. You may have food sensitivities or allergies, might want to explore that.
I would think that if you googled something like "starch food" you could find some lists.
Pretty much all grains are starchy. So are many root vegetables like potatoes, sweet potatoes. I believe bananas are starchy although not sure. Those are the main starches but that is by no means a complete list.