Pellets

All wood products produce smoke when burned - but smoke can be void of flavor. The flavor of any tree is in cambium layer - the  actively growing part of a tree that is found under the outer bark. This means that pellets made from by-products of core kiln dried wood from a hickory furniture or hammer handle factory are almost void of
Flavor with no (or a very weak) carryover from the growth in the cambium layer which is destroyed when the bark is removed and wood is processed. When the "old timers" gathered wood to smoke food they did not take the bark off the wood. They kept it to protect the flavor.