Here is my best 5th grade interpretation:
>I placed a jar in Tennessee,
Literal, rural landscape comes to mind
>And round it was, upon a hill.
Literal, although the hill might just be a high place
>It made the slovenly wilderness
>Surround that hill.
I had to look up what slovenly means(it means untidy)
I think this line means either 1) the environment was captured within the jar's reflection(sorta like this) or 2) something about the jar commands attention like there's something special about it. akin to becoming the "center of the room"
>The wilderness rose up to it,
>And sprawled around, no longer wild.
This means that nature gradually becomes less wild as it reaches the top of the hill; less wild as in less trees/plants/life in general. sprawled meaning trees descending into grasslands. this could mean that jar is able to make what is wild refined.
>The jar was round upon the ground
The jar is flat on it's bottom, not on it's side; steady and sturdy
>And tall and of a port in air.
To me tall doesn't mean it's literally a tall jar but instead I think it means the Jar is particularly clean/shiny/brilliant and standing tall as if it's proud of itself. port of air meaning it's got a wide mouth that air can easily pass through. This can mean while it is steady it is not stubborn to change and flow
>It took dominion everywhere.
>The jar was gray and bare.
Basic, fundamental, raw, commanded respect
>It did not give of bird or bush,
Bird meaning scared, skittish and bush meaning passive, grounded, unmoving. this line reminds of of another poem that is about emotional stability. check it
>Like nothing else in Tennessee.
alright bro that's all i got, hope that helped