I have been checking the sources of several old tunes used in carols and hymns.
Sherburne is taken from Mendelssohn-Bartholdy, so is German, not American.

There are several manuals of tunes and chants. One that was reprinted many times was the "Bristol Tune Book" ed. by Alfred Stone and published in England by Novello et. al.; old copies should be obtainable for very little. Mine has music for 758 tunes, later editions have 900 or more.