Not quite grafting?

Hi all, a few months ago i planted papaya seeds all around my yard just to see if any would grow with the stun (sheer total utter negelct) method. only one did. it grew out of the massive roots of a huge tree. i know this is not quite grafting but i believe that the papaya is using the water and nutrients from the tree by tapping into it's roots. has anyone ever seen this happen or know of a way to make it happen? i was thinking of trying to dig out holes in the roots and plant seed there.

I tried to take a picture of it today but the camera on my phone is not working. i will get a pic up asap. im also going to use my drill to make holes in the roots and put some compost and seed. im not sure what kind of tree it is (banyan maybe) but it has huge roots exposed all over. the area might just become my root graft garden.

finally got some pics.