Are there mythical elements in "Barn Burning"?
I think that there are certainly many archetypes that are evident in mythology that can be identified in this story of self-knowledge and mature development. To me, the motif of the young Sarty choosing to betray his father and then leave his family and by implication leave his father's unscrupulous attitude towards property and law finds many echoes in similar characters who leave everything they have known and set out on a quest by themselves to find a new life. Consider the motif of the journey and how this is echoed in so many epic classics such as The Odyssey and other myths.
Consider how Sarty is persented at the end of this excellent tale:
The slow constellations wheeled on. It would be dawn and then sun-up after a while and he would be hungry... He went on down the hill, toward the dark woods within which the liquid silver voices of the birds called unceasing--the rapid and urgent beating of the urgent and quieting heart of the late spring night. He did not look back.
Although he is depicted as suffering from profound isolation and loneliness at the end of the tale, there is a sense in which this is actually a liberation for him, that leaving his family has helped him to find himself as the "constellations wheeled on" and he walks into the "quieting heart of the late spring night" without looking back. Through the motif of the journey and the departure, which is captured in so many mythological tales, Sarty finds release.