A collection of Welsh poetry in the hand of Elfyn as well as copies of his work in the hand of his son, C. Elfyn Hughes and John William Jones of Tanygrisiau, Merionethshire. Numerous compositions were entered in Eisteddfod competitions. Some are printed. There are also letters addressed to Robert Owen Hughes from various correspondents, mainly on the subject of poetry or regarding articles published by him in his newspapers, 1886 - 1918.
A lecture by Elfyn on Islwyn is undated. Also, there are notes and articles on Elfyn by C. Elfyn Hughes and J.W. Jones aforementioned, 1892 - 1952.