You find sea bindweed (Calystegia soldanella) by the sea. I Know that is stating the obvious but as, superficially, it is very like field bindweed it is one of the quickest ways to tell them apart. Sea bindweed is found mainly on sand dunes and occasionally on shingle all around the coast if Britain but it is not actually common anywhere.
Both sea and field bindweed are low, sprawling plants sending out several stems across the ground from which the heart shaped leaves appear and amongst these the pink and white flowers. Sea bindweed flowers are probably a bit bigger than those of the field bindweed and the petals are a delicate combination of pink and white whereas the field bindweed can be all white, all pink, or a combination of both. The field bindweed is a weed of cultivation on farmland and in hedgerows and will never be found in the same habitat as the sea bindweed. Sea bindweed flowers from June to August.
In the USA this is called the beach morning glory but the accepted morning glory in the United Kingdom is a blue and white cultivated plant of of the same family. In Scotland it is known as the prince's flower as apparently Bonnie Prince Charlie sowed some on the island of Eriskay in 1745 when he landed to start what we know as the Jacobite rebellion. I am not sure I believe that; a rather strange thing for him to do?