Your correct, here in Illinois, you do not need a fishing license to fish your own privately owned pond or lake.

ILLINOIS RESIDENTS:
A resident sport fishing license may be obtained
by anyone who has been a resident of Illinois 30
days prior to purchase. Anglers under 16 years
of age, and persons declared legally disabled or
blind, may fish without a license. Owners or tenants
(if they reside on the land) may fish in
waters on or flowing over their lands without a
license. This exemption does not apply to club
and organizational lakes or lake developments.

http://dnr.state.il.us/fish/digest/digest.pdf (Almost 7 megabytes for those with dialup)