Well There are many edibles on the coast, as Ray Mears understands, for our ancestors, when the tide is out, the table is set.
You can eat mussels, clams, razor clam?, limpets, periwinkles, cockles, green shore crab, all I can think of, just watch out for filter feeders, they contain toxins if there has been a red tide, if I right you can only pick filter feeders in a month with "R" in it.
Here is a good page for you.
http://chrismolloy.com/www/p135