Here’s a super handy resource I use frequently – it’s a database maintained by the USDA that lists the nutritional contents of foods, both commercially prepared packaged foods and the raw materials they’re made of. I use it to check the carb counts of foods, but it’s useful to anyone trying to figure out what’s in a given food, from a twinkie to a stalk of celery. The interface isn’t much to look at but it’s speedy and has a ton of content.