Kickham, Wikipedia says, was born in "Mullinahone, County Tipperary."

The song may have been in existence in 1881:

Reading [Pa.] Times (Oct. 18, 1881) p.1:

"J. George Seltzer [a local lecturer] concluded by saying,

Oh! Scotland may boast of the thistle,
Old England boast of the rose,
But give to me that sunny bright spot,
Where the dear little shamrock grows."