Suddenly a low voice murmured:

Gil-galad was an Elven-king.
Of him the harpers sadly sing: the last whose realm was fair and free between the Mountains and the Sea.
His sword was long, his lance was keen, his shining helm afar was seen; the countless stars of heaven’s field were mirrored in his silver shield.But long ago he rode away, and where he dwelleth none can say; for into darkness fell his star in Mordor where the shadows are.
The others turned in amazement, for the voice was Sam’s.

‘Don’t stop!’ said Merry.
‘That’s all I know,’ stammered Sam, blushing. ‘I learned it from Mr. Bilbo when I was a lad. He used to tell me tales like that, knowing how I was always one for hearing about Elves. It was Mr. Bilbo as taught me my letters. He was mighty book-learned was dear old Mr. Bilbo. And he wrote poetry. He wrote what I have just said.’
‘He did not make it up,’ said Strider. ‘It is part of the lay that is called The Fall of Gil-galad, which is in an ancient tongue. Bilbo must have translated it. I never knew that.’

Book 1, Chapter 11 A Knife in the Dark