According to some people, an itchy left palm means money is coming your way, while an itchy right palm means you’re about to lose money. Others believe the same thing, but with left and right reversed.

Therefore, Stalley can feel the moeny coming in because of his palm itch.

Does an Itchy Palm Mean You'll Soon Make Money? — Dailybreak

But back to itchy palms. When the Saxons met the Celts, their two superstitions got mixed together over the years. Eventually, people on the British Isles (where Celts and Saxons lived) started to believe that the only way to itch a scratchy palm without undoing its good luck was by scratching it on wood.

Later in the song Jack states “With you I’m still alone.” A significant other has caused him to be paranoid and it is consuming him and it is everywhere he looks. This may be the cause for him wanting to go to that lonesome valley because he is heartbroken and believes there is nothing else to live for.

Referring back to the sample and title of the song, Jack is clearly letting go of everything and wants everyone to let go of him and just let him die alone and at peace

In the movie O Brother, Where Art Thou? In the last scene of the film, three prisoners are digging graves for the three main characters. They begin singing “Lonesome Valley” (The sample which is in the song).

Lonesome valley is referring to his death. Going to a place where there is no one else.

When he lights up his blunt, he gets light headed and high up in the air and feels very light.

When he writes, he runs with it and lets it consumes him and does the best he can to be the best. “Take it and run with it”