The ancient seer Yajnavalkya studied the Yajurveda collection under the tutelage of his maternal uncle. Yajnavalkya was a really fast learner. He and his uncle came to have serious differences in interpretation. On one occasion, his uncle was so enraged that he demanded the return of all the knowledge he had imparted to Yajnavalkya. Yajnavalkya returned in indignation or (literally vomited) all the knowledge he had learnt.
After having spewed out the knowledge had from his teacher, Yajnavalkya adhered to the Sun God and got new knowledge directly from the Great One (original man, Narayan) who taught him the Shukla (White) Yajurveda.
Yajnavalkya is now esteemed as one of the founders of Indian civilisation, an eminent sage - and so on.
Now, the subject-matter of the two collections - the Black and the White Yajur - is almost the same. But the white is more systematic and contains some added texts. [Yaj, inside cover; also: ◦Link]
Yajnavakya taught one of his two wives the Brihadaranyaka Upanishad.