Common varieties of borage have prickly leaves and small pink/purple/blue flowers (colour variance occurs upon the one plant). Borage is an annual, but is very succesful at self-seeding. The flowers can be put in salads, cordials, and beers. The young leaf is used as a herb and salad green. Borage is reputed to give the drinker courage, making borage beer reputedly a drink to have before going into battle. (for beers, see Brewing)
Did you know?: Borage leaves are supposed to have high levels of magnesium, and when put on a fire are supposed to make a minor fireworks display. I've tested small quantities of fresh borage leaves, but no sparklies. Perhaps whole branches of dried borrage on an open fire would work?