Norbourn
From Tolkien Gateway
Norbourn was a river in the Northfarthing of the Shire. Between it and Brandywine River stretched Greenfields, where the Battle of Greenfields was fought.[1][2]
Identification
Norbourn is only mentioned in the detailed index J.R.R. Tolkien was preparing for The Lord of the Rings, but which was eventually left unfinished. In the map A Part of the Shire an unnamed river flows from the north to the Bywater Pool. It might be Norbourn, though it is also possible that Norbourn flowed straight to Brandywine more in the north.