Virginia Knight:

>Mahler set some of his own poetry in the 'Lieder eines fahrenden Gesellen'
>and 'Das klagende Lied'.  I can think of some other cases where a song text
>is attributed to an otherwise unknown poet and I've wondered whether the
>composer is setting his own words under a pseudonym.

Elgar did this, both under his own name ('Owls') and under noms de plume
such as Richard Mardon ('Zut, zut, zut').  (He also set verses written
by Alice).  His song 'The Wanderer', written for an American male-voice
ensemble called the DeReszke Singers, is a setting of an anonymous 17th
C poem he found, to which he added an opening stanza written by himself.

Alan Moss