What do you bring to lunch to eat at your desk?

I just started interning at an office in a neighborhood with nothing worthwhile in the way of takeout--it's all expensive and doesn't even taste good. On top of that, I want to save money, but I don't know what exactly I should bring in to eat.

I'm sure you guys have a lot of good tips and tricks. What are your favorite recipes to make and bring to work for lunch?