Find a data source for food nutrition info

Before I can compute a crop with an optimal nutritional yield, I have to know what nutrients are provided by each one. Today I found this dataset that looks like a good place to start.

They cite the USDA Agricultural Research Service as their source, which seems credible. I'm going to take it on faith for now so I can stay focused on getting some code working, but I'm also flagging this post for later verification so I don't forget to come back.