Mark Cahill is the guy with the wild rumors of fish being there and the story of not finding them.
I don't know if they're there now, but at times of the year when they are you can flyfish well along the Hingham Harbor side of World's End (also along the Weir River side). You can get a backcast into water from where the Lincoln sailing club has its docks, but it's pretty featureless water and I'd only do it if I saw breaking fish.
There's more, Mark has written about it around here somewhere, but I have stuck to World's End when fishing Hingham.