Explanation:
its about the good ole south
In this passage, Nick reflects on what the landscape must have looked like when the Dutch explorers arrived to the continent. He is looking at Gatsby's house, and at this point in the novel, we know that Nick believes that New York, as well as the people he has met, are vile, corrupt and greedy. He contrasts this view with that of the pristine continent on the arrival of the European settlers.
The phrase "fresh, green breast of the New World" presents a view that is "fresh." The land is new, but it is also fresh in the sense that it is not rotten. The land has not yet been "infected" with the corruption of modern times. Therefore, the phrase is intended to represent a time before America had become a land of greed and vice.
This lines could be seen as examples of sensory imaginary. More precisely it is connected to smell because of the potato and sight because of how this person is found "sitting, surrounded.." it might be said that the combination of these two images could give the reader a vision of what the writer is trying to convey.