I have for many years added random items to my smoking fire. Such things as herbs or various twigs, really anything that might add a bit of flavor aimed at whatever the food being smoked might enjoy.
Of course, as whenever you do something that isn’t in the usual rule book, there will be naysayers and unencouraging skeptics.
However, apparently this is an ancient technique and you can see some evidence of this pedigree from this video clip concerning meatballs wherein the Swedish cook adds certain twigs and grasses to his smoking fires.
(See 1:43 for brief smoker discussion.)