Here's my transcription from the sheet music at The Library of Congress American Memory Collection: (See link above.)

THE SHAMROCK I BROUGHT FROM OLD ERIN
Thomas P. Westendorf, 1884.

1. A dear little shamrock I brought from Erin
And here in my bosom I've kept it the while.
Each throb of my heart its green leaves have been sharing
Since I came away from that beautiful isle.
The colleen who gave me the dear little token
Is waiting my coming from over the sea.
The promise I gave her will never be broken,
For she is as dear as my life is to me.

CHORUS: 'Tis all that I have to remind me of Erin,
That beautiful home where my heart longs to be;
And here in my bosom so safely I'm wearing
The shamrock I've brought from old Erin with me.

2. She stood by my side on the banks of the river.
Her eyes were as bright as the stars up above.
She vowed she'd be true, and I'll trust her forever.
The joy of my life is the thought of her love.
She took from her hair, as I left her there weeping,
This dear little shamrock and gave it to me;
And here in my bosom so safely I'm keeping
This pledge of my colleen that's over the sea.