Q.Soil for Tree in Raised Box
I have a tree in the backyard surrounded by timbers that make a box. Where can I get some free soil? And how much? What is the cheapest and easiest way to dress up my tree with a timber box around it? I’m getting ready to put landscape tarp in to control weeds.

Just a word of caution - it is inadvisable to build a raised bed around the base of the tree because it can cause harm. For more information, please visit the following link:
https://www.gardeningknowhow.com/ornamental/trees/tgen/planting-garden-beneath-trees.htm
As for free soil, you could search Craigslist or post an ad of your own. And, if you are looking for compost, I would contact your local town and village officials - many towns have compost facilities that are free of charge to residents.