Looking for information about Peter J Cosgrove

I am looking for information about Peter J Cosgrove, born 1833 in Westport, Co. Mayo. to David Peter Cosgrove and Mary. (Do not know mother's maiden name, but she immigrated to the US with Peter and his wife in1863) Married to Margaret Nolan before he left Ireland.  Peter J Cosgrove was said to have moved to St. Louis, MO upon arrival in the US with his wife and mother.  

No mention of father David Peter Cosgrove (born in 1782 in another section of Ireland) moving to the US or his date of death.  I had read an article informing me that there were very few Cosgroves in County Mayo when they were to have left the country.  We believe that they left due to being Catholic landholders and the British persecution of such people at the time.  Also, that David Peter Cosgrove was gifted the land he had in Co Mayo for his years of public service in Ireland...unsure where that was.  Peter J Cosgrove was my Great Great Grandfather.

Margaret Nolan was born in Westmeath, Ireland in 1843 to Thomas "Honest Tom" Nolan and Bridget Monahan, both of Belmullet.

This is all of the information I have about my Irish family.  Any assistance would be welcome.

Thank you,

Erin Nash-Jones