The papers consist of :
- Essays and articles composed for Eisteddfod competitions or published in journals or newspapers such as theRhos Herald, Y Goleuad, Y Traethodydd and Y Drysorfa. An array of subjects are covered, for example, religion and psychology, coal mining in north Wales, John Puleston, the hymns of Pantycelyn and Elfed, similes in the work of T. Gwynn Jones and R. Williams Parry, Dr John Charles Davies of Rhosllannerchrugog, preaching in Wales, life in Wales between 1890-1914, Dr Edward Greenly, Billy Graham and Rev. John Williams of Brynsiencyn.
- Several works concentrate on the birth place of William Phillips - Rhosllannerchrugog in Denbighshire. These essays and articles touch upon such topics as street games, nicknames, the influence of Judaism on personal names, old industries, dialect and idioms, memoirs of a native, old shops, field and street names.
- A ballad entitled Sali Ball yn Ffair y Rhos.
- An autobiography, 1880-1958.
- A diary kept by William Phillips whilst visiting San Francisco in 1914-1915 which continues up until 1925.
- 2 files of letters from various correspondents, 1916-1968.
- Notebooks whilst studying Welsh at the University College of North Wales, 1945-1946 as well as notes from various publications which also contain financial details regarding the editing of Y Blwyddiadur and Y Swyddiadur, 1956-1966.
- Indices to several publications, including Ysgrifau Beiriniadol, volume II and Y Blwyddiadur from 1957-1960.
- Sermon notes, a biblical dictionary, illustrations to the Calvinist Methodist hymnbook and bible, similes in the hymns in the Common Prayer Book and the bible.
- Notes of sermons held at Capel Mawr, Rhosllannerchrugog, Denbighshire, 1902.