You cannot say you have been to Thailand without trying food from street vendors. These vendors can be found anywhere at any time of the day.
One thing I miss the most living away from Thailand is street vendor. It does not matter where my destination is whether it is post office, shopping mall, school, or anywhere; I always see these street vendors and can have my favorite dishes at my convenience. I can easily wake up in the middle of the night and find something to eat on the main street. Here in United States, there are only few places that open past midnight let alone at 1o P.M. You can find varieties of food ranging from chicken satay, papaya salad, Pad Thai, crispy fried mussels, and Thai boat noodle.