Mongoven (Mungovan, Mongovan)

My name is John Mongoven.  I live in Orlando,Florida in the USA.  I have been researching my family for about 20 years.  I have recorded over 1,000 relatives in the USA, but have always had problems with the original Irish roots.  I travelled to Ireland in 2012 and visited the Clare Herritage Center contracting with them to give me some of the Irish history.  We are now almost a year later and I am still waiting.

To the best of my knowledge and records I have found, my family comes from somewhere near Ennis in County Clare.  The Original family was:

James Mongoven (spelled this way on his grave stone in Iriquois County Illinois, USA) - born 1801 near Ennis, County Clare Ireland - Died 1890 Gilman Illinois, USA,

Catherine Costello - (wife of James Mongovan (spelled this way on grave stone in Iriquois County Illinois, USA.) - born 1804 County Clare Ireland  - Died 1870 L'Erable Illinois, USA

Children - all bornnear Ennis Ireland.

Dennis Henry, John, Patrick J, Margaret, Catherine, Delia (Bridget)

Any info, ideas and/or help would be greatly appreciated.

John M