This is rather fun, especially if you enjoy devising your own spells or rituals within your chosen game system.
It is commonly held that magic - be it full-blown ritual or quickly-muttered spell - needs 'components' of some kind to make it happen. Sometimes it's a mundane item, sometimes there are several adventures-full of questing necessary to find all that you need... but coming up with that shopping list can be quite a challenge.
Read through these and even if none appeal or seem suitable you will likely start having ideas about what is required for the magical working that you have in mind.
Interestingly, some of the items are quite modern - just ignore them or re-tool them in terms suitable to your setting if they don't exist there - which gives a nice contemporary spin to the art of magic if a present-day or future game permits the existance of magic at all. Or even the rumour of it, that old fellow who says he needs you to find him, say, a CD-R which failed to be written on (item #91) may be deluded into thinking he's capable of magic even if your world doesn't have it!