Washington Square Park Burial Ground

I recently had the great pleasure and privilege of watching my dear friend, former roommate [:(] and fellow blogger, the inimitable Becky Abrams, perform in an improv show at the Upright Citizen's Brigade Theatre. Aside from all the hysterical laughter that one inevitably enjoys when in the presence of Ms. Abrams, the group that went on before hers did a game show sketch with NYC-themed trivia, giving me a pretty fascinating fun-fact to take home and tell YOU lucky kids about:

Did you know that there are about 20,000 bodies buried underneath Washington Square Park?
Curious? I bet you are.
potter's field: a piece of ground reserved as a burial place for strangers and the friendless poor.
(origin of use: 1520-30)

...wondering about the etymology of the phrase? you're not the only one...
Dale, from Aurora, OH, asked Yahoo! the same question on 11 jun 2003: 
dear yahoo!:
where did the term potter's field come from?
dale, aurora, oh
dear dale,
...the term "potter's field" probably derives from the gospel of matthew. in the book, after judas iscariot betrays christ, he repents and returns his payment of 30 pieces of silver to the priests before hanging himself. the priests called the coins "the price of blood" and did not want to put them in the temple treasury,  so
they took council, and bought with them the potter's field to bury strangers in.
(matthew 27:3-8)
wiki note: the site of aforementioned field is thought to be the valley of hinnom, a source of potter's clay.
so what does this have to do with washington square park?