Ask Mr. Smarty Plants

Actually, from personal experience, the soil around a recently ground stump is very good. Those small chips of wood left in the soil, as they decompose, make a good organic amendment to the soil. You will need to fill in the hole left by the removal of the stump with good dirt. When we say "good", we mean dirt that hopefully is not full of weed seeds, so don't just go out in the field and dig some up. If it's not too huge a hole, you might even consider using sterile potting soil, mixing the potting soil, native soil and wood chips together, and watering. Although you could probably plant there immediately, it wouldn't hurt to let it rest for a month or so, meanwhile watching to make sure no sprouts from the mulberry roots pop up. In an effort to survive, the tree roots left behind by the grinder may start putting out adventitious sprouts. Cut them off or pull them off as they pop up, and finally the roots will run out of stored nutrients and give up. Those roots, too, will eventually decompose in the soil; keeping the soil moist will help to speed up that decomposition.