Lots of questions on this one.

There's no military record under either Shadrack or Pleasant Mills, so we need a pension application to begin confirmation of service.
Who is Captain Fay (or Foy)? Don't see any officer by this name in a Mississippi Confederate unit. Who could this possibly be?
What about the age of this man? On the 1850 census, parents gave his age as one. On the 1860, he's 14, but in later years, his birth year appears to be 1848.

Findagrave link (copy and paste)
http://www.findagrave.com/cgi-bin/fg.cgi?page=gr&GSln=MI&GSfn=p&GSpartial=1&GSbyrel=all&GSdyrel=all&GSst=27&GScntry=4&GSob=n&GSsr=121&GRid=24753565&df=all&