what is association?

association is one basis how people use magic: like bring like. if you want luck, then your ingredients should be associate with luck. to bring joy, ingredients should speak joy. some people kick up and even time spells for certain hours, days, moon phases, or otherwise.

but... where do these all come from? what if not agree with how others see?

associations often have long history in both folk magic, and folk medicine. if something grow quickly, then must mean abundance. if something have shape like body part, then surely will cure those ailments.
people look at these things, what they do and appear like on mundane level, and apply magical meaning through action.

but now, we see these long lists for what mean what, and often not context attach. why do these things mean that, well, who even care? oak is strength, and red is anger, or love, or strength as well, and full moon is full power and...
how do you remember all this?

universal... or not.

not many things show up literally everywhere in world, especially in past where many associations come from - and even things that can find in many places often come in regional variants.

each culture and society have own traditions and rituals that shape at least some association, or vice versa.
red is blood that spill in battle - death, mourn, remember. yet red is also luck, love, joy.
white is pure, holy, clean... but also colour as leave fallen friend's skin, cold dead winters, surrender and suffer.
this all depend on who , and even when, you ask.

your association language

in good news... you do not need experiment in same ways ancestors did! to learn associations that relevant, start close to home. if you have access to books about regional folk magic, medicine, and superstition, dive in. you might even get lucky on public domain e-books from project gutenberg and similar. :)

ask people in community where possible, especially older folks: what important symbols here, what meaning? what things would someone give as friendship symbol, or in hatred? might prefer not use words like witchcraft or folk magic, but often still have tidbits that never consider before.

what if live far from home, without access to those materials? or what if not agree with any source on what something mean? do you try use that way anyway and accept holes in your magic?
this where say... take no shame in break from mould. use what have, research current region's folklore too. what still make sense, what not so much? if feel so strong that some association not make sense, then think fair say would not have desire effect in spell. maybe not go horribly wrong, but just seem... weak, fade away.
if you have happy memories prance around in geraniums, and sad memories from places bathe in yellow... then for you, geraniums might just work far better in joy spells than every yellow thing in world.