The sheet music can be seen at Duke University. I have boldfaced the differences between this and the last-posted version.

"Beautiful songs as sung by Tho's J. Farron"
THREE LEAVES OF SHAMROCK
Words and music by James McGuire.
New York: Harding Bros., 1889.

1. When leaving dear old Ireland, in the merry month of June,
The birds were sweetly singing, and all nature seemed in tune.
An Irish girl accosted me, with a sad tear in her eye,
And as she spoke these words to me, she bitterly did cry:
"Kind sir, I ask a favor. Oh! grant it to me, please.
'Tis not much that I ask of you, but 'twill set my heart at ease.
Take these to my brother Ned who's far across the sea,
And don't forget to tell him, sir, that they were sent by me."

CHORUS: Three leaves of shamrock, the Irishman's shamrock,
From his own darling sister, her blessing, too, she gave.
"Take them to my brother, for I have no one other,
And these are the shamrocks from his dear old mother's grave."

2. "Tell him, since he went away, how bitter was our lot.
The landlord came one winter day and turned us from our cot.
Our troubles were so many, and our friends so very few,
And, brother dear, our mother used to often sigh for you.
'Oh! darling son, come back to me,' she used to often say.
Alas! one day she sickened and soon was laid away.
Her grave I've watered with my tears. That's where these flowers grew,
And, brother dear, they're all I've got, and them I sent to you."