In Carl Sandburg's poem "Grass," the line "I am the grass, I cover all" appears repeatedly throughout the poem, suggesting that the grass is a metaphor for the all-encompassing nature of death. The line "voice of the last cricket" is used to describe the only remaining sound after everything else has fallen silent. Similarly, the phrase "one-kind of good-by" suggests a final farewell or the last goodbye that one might give to a loved one. By comparing the "voice of the last cricket" to the "one-kind of good-by," Sandburg is drawing a parallel between the fleeting and ephemeral nature of life and the inevitability of death.
As for the setting for the "good-by," it could be any number of scenarios, such as a soldier bidding farewell to a loved one before going to war or a dying person saying goodbye to their family members. However, the poem does not provide any specific context, allowing the reader to interpret the setting as they see fit. The vagueness of the setting reinforces the universality of the theme of death and the transience of life that the poem explores.