According to the Department of Veteran's Affairs Nationwide Gravesite Locator, the W. Pratt in Memphis:

PRATT, W
PVT US ARMY
CIVIL WAR
BURIED AT: SECTION B SITE 1187
MEMPHIS NATIONAL CEMETERY
3568 TOWNES AVENUE MEMPHIS, TN 38122
(901) 386-8311

There is also an unknown Pratt in the Memphis National Cemetery listed as:

PRATT, - - -
UNK US ARMY
CIVIL WAR
BURIED AT: SECTION H SITE 13807
MEMPHIS NATIONAL CEMETERY
3568 TOWNES AVENUE MEMPHIS, TN 38122
(901) 386-8311

Jim Martin