How to eat with less than 3$ until next week ?

I have been trying to eat without feeling guilty afterwards, and I am quite proud of myself. I have been doing good with food for the past three weeks.
I had to pay University fees for next semester this month though and thus I only have like 3$ for the week.
Since I am new to the whole eating things that are not ice cream for breakfast and then tears for the rest of the day, and balance diet and everything. I have no idea what to get. And I fear I might spend my last 3$ on something useless.
I have a pack of rice, and a pack of flour.
Do you have any suggestions ? Something that could last until then maybe ?