I have a couple of links that are my usual go to sources for nutrition content of various food items.
The first one is https://nutritiondata.self.com/ which is easy to use but is a bit dumbed down relative to the link to follow. It derives all of its information from a USDA Agricultural Research Service database which you can access from the following link:
https://www.ars.usda.gov/northeast-area/beltsville-md-bhnrc/beltsville-h...
This link has broken the database down to a number of downloadable pdf files by food type. It is worth downloading the ones of interest to you for later use even when you do not have internet access. These are extremely detailed as to nutrition content and provide data for foods that you probably have never heard of. Do you want to know the amount of Phenylalanine in 100g of boiled Lotus root? No problem, its there. These are big files, if you are on dialup it sucks to be you.