The Gawain Poet is chiefly known for his epic Sir Gawain and the Green Knight. It's a masterpiece of courtliness and mysticism and not at all about knights jousting and clouting each other with their swords. One MS contains the four poems attributed to the Poet, though in the handwriting of a scribe, not the man who composed it. The picture shows the first page, with the Green Knight himself holding up his decapitated head to the axe-wielding Gawain.
The Gawain Poet's circle was very different from that of his contemporary, Geoffrey Chaucer, and no one ever reported him performing at the royal court, like Chaucer did in this picture. His language is less fashionably modern and uses the old alliterative form. Geoffrey seems to be reading from a pulpit. The Gawain Poet was more likely a traditional oral poet, like a bard, though eventually his compositions were written down, probably by someone else.