Most bang for buck when planning food budget?

I recently got a salary increase which means I'll be able to increase my monthly food budget from $90 to $120.

This means I'll have $4 to spend on food per day as opposed to the $3 I spent before. Currently I mostly eat rice, beans and lentils.

I'm wondering what would be the most bang for buck upgrade to my food budget? I was thinking maybe protein shakes? This would make sure I always hit my daily protein goal, something I've struggled with in the past.

I was also thinking about incorporating more vegetables to my meals, canned tomatoes and frozen spinach maybe?

Any thoughts and ideas? 😊