Searching for Patrick J. Murphy

I was at an Irish Festival recently and was told of your website. 

I have been searching for the birthplace of my GG Grandfather – Patrick J Murphy born in Ireland about 1838 (on his death certificate it shows October 17, 1837 as his birthday).  I have a Virginia Marriage Certificate from 1862 which shows he married Margaret Tierney born in 1842, also from Ireland; his parents were Edmund Murphy and Hannah (no last name); her parents were John Tierney and Hanna (no last name).  This is documented proof and I know this to be true as I followed his journey to Baltimore, MD and worked for the B&O Railroad his whole life, retired and died in 1925.  His son Edward married Annie O’Connor whose father was William O’Connor from Ireland. Edward is my great grandfather. His son, my grandfather, was Basil Patrick Murphy who married Mildred Campbell and her mother was Mary McCaffrey whose father was Daniel McCaffrey from Ireland.

I have searched each surname and hit a wall as to where in Ireland these ancestors were born.  It’s very frustrating and I have just about given up. 

My family is going to return to Ireland this year and our hope was to visit the area where our ancestors were born.  Our DNA shows Galway and Ulster (Louth, Monaghan).  However, my mom had told my daughter that the Murphy’s were from Cork.   

I have searched Ancestry and My Heritage, looked at Geni World and Family Search  and Roots Ireland to no avail.  I’m writing to ask if there is any other site or heritage center that would help in my search.

Thank you for any assistance you may provide.