I am also looking at this couple. I believe they had a son, Levi E. Wilcox, born May 1829 (source: 1900 US Census, Oklahoma Territory), born at Moores Hill, Dearborn county, Indiana (source: Civil War muster roll entry, State of Illinois). He enlisted at Monmouth, Warren county, Illinois in 1862, and was discharged at Nashville, Tennessee in 1865. In 1866, he married Sarah Gertrude Smiley in Warren county. In the 1870 census, they are living in Ringgold county, Iowa with a young daughter, Laura, born in Illinois. They are listed as having their 5th child, and unnamed son, on 9 October 1886 in Union township, Worth county, Missouri (source: Missouri birth records). In the 1900 census, Sarah listed that she was the mother of 8 children, 5 living, but only son Levi H. was listed in the home - born 1888 in Iowa.
Levi filed for a disability pension from Oklahoma Territory in 1893(?). Sarah filed for a widow's pension in 1908. They are buried at Prairie View cemetery, Kay county, Oklahoma. This is all I have found on the couple at this point. It's possible that obits might have been published in Monmouth, as Sarah had quite a few family members who remained there. I will try to find those, but I'm not sure what years have been indexed. I don't have specific dates of death yet.
If anyone has any questions or comments, please let me know.