Not sure if this is a useful as they are not quite poems, but you might be interested in exploring
Welsh Triads. Basically, they were used to easily call to mind the thousands of pieces of info bards had to remember, but they became an art form in their own right.
(from the above site)
Three Generous Men of the Island of Britain
Nudd the Generous, son of Senyllt,
Mordaf the Generous, son of Serwan,
Rhydderch the Generous, son of Tudwal Tudglyd.
And Arthur himself was more generous than the three.
Three Faithful War-Bands of the Island of Britain
The War-Band of Cadwallawn son of Cadfan, who were with him seven years in Ireland; and in all that time they did not ask him for anything, lest they should be compelled to leave him;
and the second, the War-Band of Gafran son of Aeddan, who went to sea for their lord;
and the third, the War-Band of Gwenddolau son of Ceidiaw at Ar(f)derydd, who continued the battle for a fortnight and a month after their lord was slain.
The number of the War-Band of each of those men was twenty-one hundred men.