Use the tree part. It grows on WOOD chips, not bark chips. Remember, the bark is designed by the tree to have special medicines in it to stop fungus from taking it over, to protect the wood. You want the wood. Also bark dries out faster=death for fungi.
Thanks John... is there a size limit for the chips? I have access to some chips from the local power company, but the chips might be 1-2 inches. Is that too big? The advantage is that they would be very fresh... as in just cut. and, I would know what kind of wood it is.
That's not a problem. Sticks, like 4-8 inches long and 1-2 inches wide, won't inoculate well, but those chips should be fine. Keep them moist. I would put cardboard down on bare soil first, then spawn, then chips. I would put straw casing on top to keep moisture in and sun out.