I want to lose weight by eating only a few healthy foods. Any suggestions?

I weigh 140 pounds and I am 5 feet 1 inch tall. I have 3 months before a family reunion and I'd like to look and feel better. I've been exercising 4-5 x per week. I have already lost 7 pounds. My question is this..what FEW foods do you recommend for me to eat that are healthy, VERY quick and easy to prepare, and I could alternate eating several times per week and have a completely healthy balanced diet? I really want to be able to buy only a few kinds of foods in bulk and stick to them as long as possible. Any suggestions?