where is he from?
The eponymous Lincolnshire hamlet of Greenfield.
William Greenfield
Greenfield was born in the eponymous Lincolnshire hamlet of Greenfield. 
what was the keldholme priory election dispute? The dispute occurred in Yorkshire, England. who was the dispute between? Archbishop of York and other nuns. and what was the dispute about? His candidate, Emma de Ebor', was  unacceptable by many nuns. who was the archbishop then? William Greenfield. when was he born? The date of his birth is now lost.
wiki:20666814
William Greenfield [SEP] Early life
Greenfield was born in the eponymous Lincolnshire hamlet of Greenfield. The date of his birth is now lost yet we know that he was related to a predecessor in the See, Archbishop Walter Giffard, who paid for the young Greenfield's Oxford education in the year 1269. Giffard instructed that his bailiff at Churchdown (near Gloucester), "...to pay to Roger the miller of Oxford twenty shillings, for our kinsman William of Greenfield while he is studying there, because it would be difficult for us to send the money to him on account of the perils of the ways". Greenfield next studied in Paris, where he became a doctor of both civil and canon law.