help with a short trip

i think i may have registered for college a bit late, which means if im not able to go this semester, i'll have a semester off. so, if im not going to school, i've decided i'd like to take short trip from south texas, to north louisiana, to central texas, and back to south texas. maybe three weeks or so? i plan on backpacking and camping along the way. im probably going to bring about $200 an i'll have my ATM card in case of emergency. i'm also going to bring a cantina for water, a tent, a change (or two) of clothes, a light sleeping bag, and a few personal items (book, sketchpad, etc.) any advice? tips on what else to bring? tips on places to find free food? anything?