Thank you all for your responses. I haven't read any books on the subject of past lives before, in fact up until now I hadn't really even thought much about it. Obviously I'm open to the idea, and given what my son is experiencing and talking to me about, I certainly can't discount it!
I feel...
My son is just about to turn four. His entire life we've called him an "old soul" as he's been seemingly wise beyond his years, acts very much like an adult (and prefers the company of adults), and somehow knows things that he just, well, shouldn't. He has been working with farming equipment...