[we will presume you have nice smelling tap water.]
first change the $1 wax seal. examine the floor flange under the wax
and fix it if needed.
there are some modern non-wax seals available now.
see:
www.fluidmaster.com


Joe wrote:
There is an odor that is coming from the toilet.
This usually occurs first thing in the morning (after toilet hasnt been
flushed for several hours). Smell goes away after flushing, but will
come back the next day.

TIA for any help.