The "welcome" sign seen when entering the city on Mamaroneck Avenue references back to the founding of White Plains, when a group of settlers from Rye purchased this land from Chief Pathunck and the Siwanoy Indians. The purchase deed, reproduced in the document above, simply states that the cost was "a valuable sum of money". This deed superseded (after years of litigation) an earlier claim on the land by John Richbell, whose estate claimed that both White Plains and Scarsdale had been previously ceded to him by the Mohegan Indians.
This is a well traveled road, so if you choose to park in the Saxon Woods (north) lot, take care when crossing the street. Better to park off of Purdy Avenue, which will give you a much more direct approach to the actual cache.
Bonus Question: Please do NOT post any spoilers or pictures answering this bonus question! In what year was the Deed for White Plains signed? [Edit: This date used to be shown on the White Plains welcome sign found at the waypoint, but that sign has since been replaced; a picture of that original sign is now attached to this cache listing as a "Spoiler".] Noting the answer to this question may come in handy for future adventures...