The quiet, peaceful, rural landscape is established in the opening line of the poem, where we are told that there is "never a sound beside the wood" but for the sound of the laborer's scythe swinging through the air and the grass. A little later, the poet describes "the heat of the sun," as well as "feeble-pointed spikes of flowers." Thus, altogether, the poet creates a setting which evokes beauty and tranquility. This is appropriate as it reflects the main theme of the poem: that work, and specifically physical work outdoors, is a peaceful and enriching experience.
In the second half of the poem, the poet describes the laborer's work as one of "earnest love" and "the sweetest dream." These descriptions suggest that the laborer's work is noble and a labor of love. The idyllic description of the setting reflects the speaker's state of mind as he works. The fact that this poem celebrates the laborer's love for his work is also emphasized by the form of the poem; it is a sonnet. A sonnet is a poem which usually celebrates love.
Throughout the poem, the poet repeatedly emphasizes the quietness and peacefulness of the setting. He repeatedly describes his scythe as "whispering" and he also describes "the lack of sound." This quietness seems almost reverential, and suggests the respect one might usually associate with a place of worship. The implication is perhaps that the field where the laborer mows the grass is, for him, a kind of church. It is a sacred, peaceful place, and a place suited to reverence and meditation.