Although he is not Finn MacCool, this man gained knowledge after burning his thumb on a potion of knowledge, after which he transformed himself into a grain of wheat to evade the vengeful sorceress Ceridwen.
This man instructed a jockey to throw down his cap at the spot where his horse stumbled; when he later ordered that spot be excavated, he discovered a pot of gold that he used to repay his master. This man tricked his rival Heinin Vardd so that he was unable to say anything other than "Blerwm, Blerwm" in front of the king. This man advised his mistress to disguise her maid as herself in order to avoid the advances of (*) Prince Rhun. Although he is not Finn MacCool, this man gained knowledge after burning his thumb on a potion of knowledge, after which he transformed himself into a grain of wheat to evade the vengeful sorceress Ceridwen. For 10 points, name this Welsh "chief of the bards" who names a Frank Lloyd Wright estate in Wisconsin.
This man instructed a jockey to throw down his cap at the spot where his horse stumbled; when he later ordered that spot be excavated, he discovered a pot of gold that he used to repay his master.
Taliesin [or Shining Brow; or Gwion Bach ap Gwreang]