There's actually a simple recipe for that, but it doesn't involve Rodinal.
This was used by the news photographers back in the old days because it does get the job done. You can be sure to kiss the smooth gradation goodbye with this one.
Take some Tri-X and expose it at EI 3200. Then heat some Dektol to 70°F and soup the film in that for 6 minutes.
This is sure to give you grain like you wouldn't believe.
In the UK, the same trick was done with HP5 and PQ Universal.
To make things better, just expose it on grade 5 paper!
And for even bigger grain, use the Lomography POP9... it makes 3 frames wide and 3 frames tall on a single 35mm frame.
Then you can call the grain monster