The definition of poetry by eNotes.com states that..."most poetry simply seeks to convey emotions or ideas." The speaker's emotions are easy to spot in this poem: he is nervous and scared, which has a strong bearing on the leaving of the note. The main idea deals with Jimmy's brother Minnegan.
James Wright was a poet that never seemed comfortable with his writing, regardless of the form it took. However, it is noted that...
Throughout his career...he was esteemed for his musicality, imagery, and humanity.
So what strikes me first about Wright's poem, "A Note Left in Jimmy Leonard's Shack" are the poet's uses of imagery:
Your brother Minnegan, / Flopped like a fish against the muddy ground. / Beany, the kid whose yellow hair turns green...
You told me once that the waking up was hard, / The daylight beating you like a board.
The other aspect of Wright's poetry that makes such an impact is his humanity—his ability to tap into the human side of his poem's characters.
In this poem, the speaker and Beany find Jimmy Leonard's brother, Minnegan. Beany sends the speaker to find Jimmy to tell him that his brother is dead, though the speaker is not sure if Minnegan is alive or dead. However, the speaker is frightened to face Jimmy with the news.
Jimmy obviously drinks a lot and the speaker is afraid to wake him drunk, especially as Jimmy has described how painful it is to wake up. Waking up to news of his brother's death also frightens the speaker in that he is afraid that he will be blamed somehow for Minnegan's condition.
Beside, you told him never to go out
Along the river-side...
You might have thrown a rock at me and cried
I was to blame, I let him fall in the road
And pitch down on his side.
The speaker is also afraid for the trouble he will get in when his parents find that he has been where he does not belong—at Jimmy's shack:
Well, I'll get hell enough when I get home / For coming up this far...
It is at this instant that the reader realizes that the speaker has left a note for Jimmy, running to his shack and back. I believe it is the speaker's fear that makes him leave the note rather than trying to tell Jimmy himself. The speaker intends to tell his father where to find Jimmy and what has happened, we can only assume that in this way his dad can face Jimmy. Therefore, the speaker must be more frightened of Jimmy than getting in trouble at home. We also get the sense that the speaker may not be as old as Jimmy if he turns to his dad for help.
And while the poem moves on, the speaker is telling Jimmy he had better find Minnegan before the police do. This may be what is in the note, or the last paragraph may reflect the note's contents. The speaker repeats that Jimmy had best get to his brother fast—though he's not sure if Minnegan is dead or dying, but the speaker has gotten sick, Beany has gone home, and Minnegan is dead or dying, "rolled in roots and garbage like a fish."
Booboosmoosh is right except for Minnegan is found unconcious and not yet dead. It is unclear to the speaker whether, "He's drunk or dying" since the term "drowned" in this particular section of Ohio could mean drowned in the river or drowned in his drink, aka drunk. In the poem Wright also said, "you told him never to go out/along the river-side/ drinking and singing". Which allows the reader to know that Minnegan would be in trouble if he was found drunk. This creates the fear of misplaced anger. The speaker would have to worry if he would be blamed for Minnegan's mistake. Also the line, "I let him fall in the road" shows that Minnegan was not in the river but in the middle of the road. Also there would be no need to worry about the police if Minnegan had died from drowning in the river. That particular action would have not been surprising of the place and time period. Thus, little to no action would have happened because of a drowning death. Which leads the reader to believe that Minnegan is drunk in the middle of the road and not a recent death of drowning in the river. However, the complete answer is uncertain because the speaker doesn't clearly say which possibility it is.