this is my mahogany--always a favorite. i was going to try ebony, but it stumped me completely using this method.
this was a many-layered effort. the mahogany board i used as an example had very dark parts where the knots were and then a variety of different shadings in the lighter part of the wood.
i added some wide lighter lines in the middle and on the left in a separate layer and used the blur filter, smudge tool and liquify filter to spread them out.
i also added thin dark lines and smudged them.
with some of the extra dark lines,you'll notice that they don't look a bit like mahogany. i was using the reflection setting in the liquify filter and got something that looks like the grain in some kinds of pine. i didn't choose to do a piece of pine but wanted to keep that grain in so anybody who wants to do pine could see it.
it was sort of an accident and i tried a number of times to duplicate it and it's difficult to do and requires more time and patience than i wanted to devote.
i spent a childhood imagining i could see faces in the knots of the knotty pine walls in my bedroom and i've had just about all the knotty pine i care to deal with thank you very much. ;)