i'm not so sure about foods but i have nights when i wake up about every 15-20 minutes. here are a few things i've found really help me sleep better
yoga-10 minutes before bed (especially if you can find a pm yoga video) really calms me down to get me into a good mind frame before bed and helps me stay asleep through the night
white-noise- i know it sounds cheesy, but it really works. especially if you live in a noisy area (i live on a lake with bullfrogs and crickets...i used to live in the city...so much worse). a lot of times small noises wake us and we don't realize it. putting on a fan or even d/l a white noise ap on an ipod (i like whale/ocean sounds) will drown the small ones out and help you stay asleep
turn off all the lights-even small lights like the cable box, your laptop, power strip, etc. can effect the body's levels of melatonin (or so my doctor told me). i put electrical tape on them to blackout my room
lavendar spray- the smell of lavendar is really relaxing. i picked up some lavendar body spray at the dollar store and spray it on my pillow. even if it doesn't work, it smells really good
i hope some of these work for you. also, i try not to eat anything within 2 hours of bed. i find on nights i do, i wake up more frequently.