How does imagery develop the setting in the opening paragraphs of the story "The Flowers"?

The opening paragraphs of "The Flowers" portray a pastoral scene of rustic and natural beauty and peace. 
Walking outside at a sharecropper's farm, Myop delights in nature:

The air held a keenness that made her nose twitch. The harvesting of the corn and cotton, peanuts and squash, made each day a golden surprise that caused excited little tremors to run up her jaws.

This young girl is much like Rousseau's Natural Man who is spiritually and mentally free since he is not tied to any of the artificial needs that depict modern society. Myop delights in the music of her stick tapping on the fence, the sun on her face, the "tiny white bubbles" of the stream against the rich, black soil.
These opening paragraphs depict the beauty of pristine nature with visual and auditory imagery, such as the pretty "silver ferns" and wildflowers, along with the sounds of her stick tapping out a tune on the wooden fence. For instance, one passage describes Myop discovering

...an armful of strange blue flowers with velvety ridges and a sweet suds bush full of the brown, fragrant buds.

All the more shocking, then, is the brutal contrast of the ending of Alice Walker's story as this idolized version of the rural life of Myop is disrupted and soiled by her sudden discovery of the remains of a man of her race who has been hanged and left to decay by the perpetrators.