Patrick Duffy/Mary Fitzgerald; Patrick and Thomas Fitzgerald

My great grandparents, Patrick Duffy (abt 1835-1867) and Mary (Fitzgerald) Duffy (1836-1920) were born in Irish Free State,  Ireland which relatives remember as Cork, Ireland.  They were married abt 1853 and immigrated to the USA before 1855.  Their children:  Julia 1855 – 1934; Michael 1856 – 1898; Mary E. 1859 – 1937; Margaret 1867-1940 (my grandmother) were born in La Salle County, Illinois.  They were farmers.

Patrick Fitzgerald was the father of Mary Fitzgerald.  He did not immigrated to the US.   Mary also had a brother, Thomas Fitzgerald (1820-1898) born in Ireland, immigrated to the US, died in La Salle County, Illinois.  Thomas , also was a farmer, never married.

I am looking for any information about Patrick Duffy and Mary (Fitzgerald) Duffy ; Patrick and Thomas Fitzgerald.