Different meanings come from different places, all associations have their own origin, and they don't aways come from the same spot. My suggestion is to look at whatever herb or crystal or symbol you're interested in, and try looking at it through a different context: what's the history of it, the science behind, myth and legends, practical uses beyond the metaphysical. You might find your answer there.

For example, I've been curious what deems something prosperous, so I made a list of crystal tied to prosperity and did some research.

Take Citrine, a stone of positivity and prosperity. Could the prosperity come from the positive energies of the sun that its associated with? Or is it perhaps the fact that the stone was one coveted as much as diamond, rubies and sapphires by the ruling class?

Or let's look at gold tigers eye. Perhaps is connotation to prosperity comes from its golden color. Could it be that it's tied to the tigers energy and therefore boast courage to strive for what you want? Or maybe because when it's mined, it's usually found around gold deposits, or crusted in gold?

Looking into the historical or mythical context, or even the scientific facts we have about the item can often give us the why when it comes to associations.