Here is a setup I did mostly for a marble texture to disrupt repetitiveness for instances using object info/random, but for a flat plane I would use some random color generator instead (bricks texture can do this using the same noise setup) . It uses last noise component to drive random rotation for each tile/plank/whatever, but for wood which is strongly directional in nature I would use it for something else. Multiplying in some darkness for variation maybe? The setup looks like this, with the two textures in the center showing what the inputs actually are - kinda hard to see that it is a (still needs to be seamless though) repeating texture:
