Not sure why I feel such a strong need to say this NOW but:
Magic doesn’t come from herbs or symbols. It doesn’t come from semi-precious stones or funky colored candles.
Non-witches use those things all the time, sometimes on a daily basis, and never really do magic using them.
Someone who doesn’t BELIEVE in the healing properties of Rose Quartz won’t benefit from them. Someone who doesn’t believe that burning a green candle can bring luck and money won’t draw those things to themselves by burning a green candle.
The magic comes from YOU. Your belief in those things is what allows them to work. Herbs, fancy candles, stones – those are all conduits and boosts for your own, innate magical power.
Do certain herbs and stones have innate power? Yes, I believe that they do. Certain days have power, certain phases of the moon have power. Not necessarily because I believe those things (aside from the astronomical/cosmological stuff like eclipses, solstices etc.,) have innate power, but because many people, over a long period of time, have believed that those things have that specific power.
However, I also feel that YOUR personal associations with a plant, stone, color etc., can override those because YOU are the one doing the magic. It is YOUR ENERGY being channeled through that particular conduit, after all. How could it NOT have some effect on the way the magic works?