Mei Mei Street Kitchen
http://www.meimeiboston.com/Mei Mei Boston is a Chinese-American food truck and restaurant company serving up creative cuisine made from locally sourced and sustainable ingredients. You can find them on a weekly changing location schedule all around Boston: http://www.meimeiboston.com/foodtruck/
Their food is very tasty and fresh and gets sold for reasonable prices. So if you see one of their trucks its definetly worth it chasing after them!
Roxy's Grilled Cheese
http://www.roxysgrilledcheese.com/As the name says, Roxy's Grilled Cheese is concentrating on grilled cheese sandwiches in tons of different variations but also some Burgers. And the most expensive item in there menu is about 7 dollars...thats a reasonable price for such a delicious meal. It is getting more and more popular in Boston, so be aware of sometimes quiet long lanes infront of the truck. It is driving around Boston during the week holding on at several prespecified locations: http://www.roxysgrilledcheese.com/locations/
Clover
http://www.cloverfoodlab.com/Clover is impressing by its very simple but at the same time very various-tasting food. Like Mei Mei, it also has trucks but at the same time restaurants to enjoy their food. The staff is very laid-back, the prices are reasonable and they also sell vegetarian stuff for those who try to avoid eating beings, that once lived. They have a very widespread location network all over Boston, so it is easy to find one of their trucks, if you are searching for a fast and delicious satisfaction: http://www.cloverfoodlab.com/location-and-hours/