I've owned a great little book called Food for Free by Richard Mabey for about 20 years, and from time to time I worry the family by bringing stuff home to cook and eat.
I have to admit that my identification skills of plants and fungi leave much to be desired, so do not take umbrage when they refuse to join me in the feast. Also, many of the 'edible' wild foods are inferior to cultivated varieties.
However, living by the sea, there are many fleshy edibles on the shore and it was time that I sampled some of these:
Rock Samphire - of King Lear fame - I tried last spring, and was good and tasty;
Alexanders (above) are popping up everywhere, and need to be tried;
Sea Kale was sampled this weekend, and I boiled the stems separately from the leaves which (according to the book) can be tough and 'like chewing a battleship'. The stems though are succulent when eaten like asparagus with butter, and were collected and sent to London in the old days. In fact, the leaves were OK, like sprout tops, as it's early in the season and they were young and fresh;
Sea Beet is the forebear of sugar beet, beetroot, spinach etc, and is currently too small to gather - I'll try this later in the year.
The rare Wild Cabbage is also to be found around here, but I don't know what it looks like (apart from being cabbage-like, obviously).