@ Kangaroobabe...
There is a better list of what the herbs do, but here is a partial...I usually delete/sell them too :)
"Here is what the herbs do:
Greanleaf- weight loss boost
lavender- prevents them from getting sleepy? (this one was unclear, but does not raise energy)
buzzberry- athletic boost (gain athletic faster if Sim exercises)
bumbleleaf- can tag and cheat on exams with less chance of getting caught, also fire resistant for a while
ginsing- energy boost
wonderpetal- studious mood boost
licorice- reduced hunger (says something like, Sim won't be hungry for a while)
chamomile- feeling social, easy to socialize with any group
cinnamon- romantic
basil- ambition (work)
sweet grass- have not tried it yet"
I just found this on one of the other threads...I know Carl's Guide has a much better list.