cycles wood material

i tried to search it in google, and then this forum, but every where i go, all i see is furnture wood, and it is not what i’m trying to make.
can some one help me with this material?
this is a light graving version:

and this is a deep engraving version:
i really need help, and if anyone would kindly explain to me how do you even get the circle bits?
i mean it looks like 3 materials added together, the wood lines, then the gravings and then the circles, which i tried with all those trigo (set a difference, and then divide it and then round it, for the sine/cosine, so that the circles apear out of no where,but how can i then make the engravings go alongst the circle?) and i can’t even begine try to describe how does the circles look like…

please help! HELP!!!

and there is also something that i never got, what is the displacent node for, i mean i don’t spot much difference (MOST OF THE TIME, NOT ALL TIMES) and it doesn’t do what a displacemenmodifier does it?