I found Mary in two census listed as white and born in Missouri.
I also found what I believe to be her death certificate here: http://www.sos.mo.gov/archives/resources/deathcertificates/
Just type in her name and when the list comes up, click on the Mary Reynolds that died January 4, 1912, Nodaway County, Cert. No. 2144. It is a copy of the actual certificate and lists her parent's names.