I am an O'Brien - my GGrandfather, Patrick "Rocky Mountain" O'Brien, was born in Caheragh Parish, just north of Skibbereen, in 1851. HIs parents were John and Ellen (Brophy), buried in Old Ardfield Cemetary, Cork. There are still O'Brien relatives in Southwest Cork, and I have been in touch with Patrick's brother John's GGrandson, Eugene (Gene) living in Skibbereen. I am sure we are speaking of the same family. John, Patrick's father, is listed on the gravestone of being from Dromore (just outside Cageragh) and Ballyva, near Ardfield. I have pictures of the gravestone. Patrick also wrote a book about his life in Ireland and coming to the US in 1868 - Birth and Adoption. My grandmother, Kathleen (1889-1974), was one of Patrick's daughters. I found my grandma's brother's granddaughter (Erin O'Brien Thayer) on ancestry.com, and we are planning a trip to Ireland in late spring, 2011.
Email me - I think I can help you.