Stump grindings make fine mulch, though they generally have a lot of soil mixed in, so it won't behave exactly like pure wood mulch.  

Let it sit a few days before you use it, as volatile gases can sometimes come off fresh mulch and damage foliage.  

Pine bark mulch can be acidic, so you might not want to use this on lime-loving plants like lilac. 

Be sure, as always, to keep mulch off trunks and plant bases by a few inches, and no deeper than 3-4".  

 Ellen