Sea plantain (Plantago maritima) is the seaside cousin of ribwort plantain and a much nicer nibble. Though a coastal plant, it can be occasionally found inland at lake shores and mountains. It should grow fine in any free draining soil as its close relative staghorn plantain (P. coronopus), also a coastal plant, is cultivated by salad growers in many areas.
A native plant to Ireland, sea plantain typically flowers from June to September in the wild. When seed heads are ripe they can be cut and hung to dry upside down in a paper bag. Enough seed will fall out for you to replant again. Seed is tiny so difficult to separate from the chaff if you break up the dried flower heads.