Good fishmongers will sell samphire. Otherwise, try looking for it at your local farmers' market.
Wash samphire thoroughly under running water before use. Don't add salt to the cooking water as it's already salty enough. Use fresh in salads or serve it boiled and dipped in melted butter to be eaten like asparagus with fish dishes.
Pronounce it sam-fire
Though there are two types of samphire - marsh and rock - only marsh samphire is widely available. Marsh samphire has vibrant green stalks, similar to baby asparagus, with a distinctively crisp and salty taste. It can be used raw in salad, though it tends to be very salty so it is more often boiled or steamed for a few minutes. Rock samphire has a rather unpleasant smell and flavour. Occasionally you may also find jars of pickled samphire in gourmet shops.
Samphire is at is best in July and August.
Choose the best:
Wash thoroughly under cold running water before eating.
Buy samphire as you need it - it doesn't keep for long. If you must, tightly wrap and refrigerate for not longer than a few days.
Details from here
"Originally "sampiere", a corruption of the French "Saint Pierre" (Saint Peter), samphire was named after the patron saint of fishermen because all of the original plants with its name grow in rocky salt-sprayed regions along the sea coast of northern Europe or in its coastal marsh areas. It is sometimes called sea asparagus or sea pickle. In Norfolk it is commonly called sampha [sam-fa]. In North Wales, especially along the River Dee's marshes, it has always been known as sampkin.
Marsh samphire ashes were used to make soap and glass (hence its other old English name, "glasswort"). In the 14th century glass-makers located their workshops near regions where this plant grew, since it was so closely linked to their trade. Many samphires are edible. In England the leaves were gathered early in the year and pickled or eaten in salads with oil and vinegar. It is mentioned by Shakespeare in King Lear: