I saw a whole lot of it in Abigail Adams Park in Weymouth (the side facing Hingham) a couple of weeks ago. But the water didn't seem too clean there, so I didn't gather any. But it's definitely in season around here.
Some Whole Foods sell it (the one in Fresh Pond does) as "Sea Beans" for something like $10/lb.
Yes, samphire, salicornia, glasswort, sea beans, marsh asparagus, sea asparagus, beach asparagus... it definitely grows on the New England coast. I wrote an e-mail to local foraging expert Russ Cohen about it last year. This is what he wrote back:
"Salicornia grows here along the Mass. coastline. Most people around here (including me) call it “Glasswort”. . . This fall my wife and I picked some Glasswort up on the North Shore and gave it to a friend who made bread-and-butter style pickles with it and it came out great. The most likely spot for you to find Glasswort is at the landward edge of salt marshes. It’s not back in season though until next spring."
I'm not sure how big it would be at this time of year with all this rain. I intended on going a few weeks back but decided it would be too young to pick.
I have also seen a photo of it taken in a local (Metro-Boston) Whole Foods. I definitely recommend asking for it at WF if you're interested, however it will probably not be local and will be from the West Coast.
You can also order from this website-- they start taking orders now, I believe. http://www.westcoastseaweed.com/seabean/nscp_toc/index.html
And just a word on foraging. Russ Cohen leads foraging walks in the area and has a book on foraging. Read more at his website: http://users.rcn.com/eatwild/bio.htm
I think it's a west coast thing, but it is farmed most of the year and should be available wholesale, if not retail. Personally I prefer the farmed product. If you are friendly with a chef, maybe you can order some through a restaurant. Purveyors I can think of who would sell it are Specialty Foods Boston, Baldor and Sid Wainer among others.