Danny Boy is a famous ballad set to an ancient Irish melody with lyrics by English songwriter Frederic Weatherly.
For fingerstyle Guitar solo or guitar and voice.
Early intermediate. 
With Tablature. With lyrics. With mp3's for audio help, or sing along.
Pages: Three pages.

Deck the Hall  is a traditional Christmas, yuletide, and New Year's carol. The melody is Welsh dating back to the sixteenth century, and belongs to a winter carol, while the English lyrics, written by the Scottish musician Thomas Oliphant, date to 1862.
Here is an arrangement for Guitar solo or Guitar and voice (classical guitar or acoustic guitar fingerstyle).
Easy.
With Tablature. With downloadable mp3 for audio help. With melody line. With lyrics.
Pages: two pages.

Foggy Dew is the name of an Irish traditional song first appearing in Edward Bunting's The Ancient Music of Ireland (1840).
Here is an arrangement for Guitar and Voice or Flute and Guitar duet.
With lyrics and Melody line. With guitar standard notation and Tablature.
Four pages (three pages both guitar and flute, 1 page flute), 2' min.
With downloadable simple mp3 for audio help and practice the Flute. Easy.

Greensleeves is a famous ballad for guitar, originated before Shakespeare's era.
For classical Guitar solo, 3 pages, early intermediate.

• With tablature, finger position suggestions.

• With downloadable mp3 for audio help

Tablature has the advantage of a very short learning curve and does not require extensive study to learn while the audio file makes the score interpreting even easier.

Guitarra Nocturno, a 19th century nocturne expressive for Guitar.

For Guitar solo (Classical or acoustic fingerstyle).

With Guitar tablature. With finger position suggestions.
With downloadable mp3 for audio help.

Early intermediate to Intermediate, 2:30' min.

Pages: 3 pages.