Frost's strongest poetic devices in "The Gift Outright" seem to be personification and metaphor, rather than imagery. Frost personifies the land as "she" and in the first line "The land was ours before we were the land's" suggests the origins and future of America.
The metaphor "deed of gift" in the parenthetical line 13 is a reference that some feel evokes the legal term which means a deed executed and delivered without consideration, no legal promise to give or donate. Frost suggests that the American culture cannot fully be developed until it develops its body and soul through giving "outright/To the land vaguely realizing westward/Such as she was, such as she would become."
In light of this poem having been read at the inauguration of JFK, this last line can call to mind the image of a new nationalism for which the new president stood.