A miscellany of sources I want to keep a finger on.
The Iconography of Early Anglo-Saxon Coinage: 6th-8th Century, Anna Gannon, 2003. Different portrait styles, including a lively abstract one
Leechdoms, wortcunning and starcraft of Early England, Thomas Cockayne, 1865. An old translation of the entirety of Bald's Leechbook; contains a recipe for oxymel.
Rush-bearing: an account of the old custom of strewing rushes, Alfred Burton, 1891. Don't trust his assertion about William the Conqueror.
The Anglo-Saxon Chronicle
The Beginnings of English Society, Dorothy Whitelock, 1952. Supposed to be a good source for wills.
The Anglo-Saxon Scop, Lewis Flint Anderson, 1903. And here I had to go to Chicago to take notes on a copy of this! Nice compilation of most of 'the usual suspects' - literature used to understand scops.
Folksong on the Faroe Islands, Hjalmar Thuren, 1908. From the Rolandskvadet effort.
Romatic Ballads, Georg Borrow, 1826. Among other things, translations from the Danish Kemper Viser, c. 1591.
Ancient Danish Ballads, Richard Prior, 1860. Another translation of some selections from the Kemper Viser. Doesn't always make clear which pieces come from which sources, but perhaps a good starting point.
The Ancient Music of Ireland, Edward Bunting, 1840. The source for "two sisters" tuning and other information on the harpers of Ireland.
Musical Instruments, Robert Bruce Armstrong, 1904, 1908. Two volumes on the harps of Ireland, Scotland and England. Detailed drawings of the extant instruments, frequently a source for builders.