i need some help/advice on how to find this elusive person.

clemens (or clement) purvis was born 1820/21 in alabama. about 1846 he married eliza hartley in miss. they settled in rankin co., miss. where they had 5 children. their son, george walter, was my gg grandfather. i am trying to find the parents of clemens and his birth county and such. my funds are limited so i'm doing all i can with no luck. thank you for any help that can be given.

lori