Disclaimer: TSA allows most food on board, with a 3.4-ounce limit on liquids and « gel » foods like yogurt and peanut butter. There’s no weight limit for breast milk, formula, and baby/toddler food. You can view a full list of permitted foods on TSA’s website.

If you’re coming into the US, check with the transportation agency of the country you’re flying from about what you can bring with you. Also, check the USDA’s website for guidance on what foods you can bring into the US. 

The former flight attendants I spoke to recommended finishing any fresh fruit and vegetables before reaching customs.