Those who guessed savannah sparrow were right! Look for these streaked sparrows this fall migration in open areas, including farmland, fields and marshes. They are often found on the ground. The yellow on the head is not always as prominent as seen in these photos. Sparrows can be tricky, which is why many birders simply lump them into the LBJ (little brown job) category. Take your time and study the patterns, bills and anything else that stands out (eye ring?) in your bird to increase your chances of a positive ID.
Here are some more photos of that savannah sparrow. Thanks for supporting Birds of New England.