collected tree

If you live in CO, I saw this post on facebook marketplace. Looks like this person has some land with a bunch of little trees that they're allowing people to dig up. https://www.facebook.com/marketplace/item/555252235677834/

The next-door neighbours had dug this 20-year-old olive out of their garden and threw it in the skip. I saw it and took it in. It is about 6in diameter at the base with some roots intact. It has no leaves on it as the top has been chopped off completely. I'm in UK and new to Bonsai. I have read...