Beach Vetchling (Lathyrus japonicus), often called Beach Pea, is a legume of beaches and other coastal habitats. The plants have compound leaves tipped with tendrils, pink/purple flowers which appear by June, and immature legumes by July.
Beach Vetchling legumes are best gathered for food when the pods are still green. On page 140 of his book Ancestral Plants, Arthur Haines recommends removing the seeds from their pods and soaking the seeds in water for at least a few hours (a treatment which he says helps to deactivate phytic acid, an anti-nutrient found is most nuts, seeds, and grains, which can bind with minerals and prevent their uptake).
After soaking, Arthur recommends boiling the seeds for 10-20 minutes. The result is a vegetable similar to store-bought green peas (Pisum sativum), though less plump and not as sweet. Learn about other uses of Beach Vetchling in Arthur Haines' foraging book.