The Field Forest Trail is a very short, runnable blue blazed trail that can be accessed via the back parking area of Coginchaug High School. To access the trail, there is a small chain link fence through which you'll have to pass, after which you'll see the first blue blaze straight ahead. At only +/-1.41 miles, this is not a long trail, but it does have some sharp elevation changes (nothing drastic), and two water crossings--when there is water running--one of which is over a dilapidated wooden bridge at around .75 miles, and the other of which is over a multi-stone crossing (I didn't take note of exactly where on the trail, so it could be before or after the bridge, but it's close). The trail takes a couple of abrupt turns, so you'll need to keep your eye on the blazes, which are easily visible. Once you reach the end, you'll see what looks like a farm gate just past the "end of trail" marker, which leads to a main road with additional parking.
There are two connector trails I found: blue/red, and blue/white (which I think is supposed to be blue/yellow if you follow the CT Walk Book), and since the option to do this as an OAB wasn't listed, I took these side trails back, finding that the blue/red was a bit overgrown, with some divots in the grass. I completed this on a humid, dusky evening, about a week after a major storm, and there wasn't anything that completely blocked any of the trails, so all were passable.