I was using burlap but the price went up a good bit, using pine straw now and notice less tar build up. Emil's smoker always smells nice, he uses old jeans. Schawee uses grass clippings, lasts quite a while and smells kinda nasty to me though. :)
Since you mentioned herb or rather herbs...
Two years ago, I removed a hive from a garage wall interior and the home owner's repair guy busted out some whacky tobaccy. I asked him to blow some of that stuff all up in the hive and we waited to see if the bees had any brownie requests but never really noticed any difference whatsoever, just since you asked! :-D