I was hoping to turn up a historic map of Middlefield online, but thus far I'm empty handed. One major lesson learned: maps of Connecticut's small agricultural communities can be hard to find. This is especially true when, as in Middlefield, they don't have a large town center.
On the upside, I managed to turn up another great historic map site. Run by the University of Alabama, "Historic Maps of Connecticut" offers images of Connecticut maps. The oldest dates from 1799; the most recent dates from 1930. Maps run every 10 to 15 years in between. Most maps cover the state, but a few are of single towns. One example covers the town of Sherman. Dating from an 1868 atlas, the image is fully interactive. You can zoom, pan and more. As always, I'm impressed.