Herb
The papery gold nobody keeps — dye, divination, and the outside of a common thing.
These are associations the community holds, not settled fact — the more a reading is shared, the bolder it sits.
Onion skins are the part that goes in the bin, and they are the part with the most uses. Boiled, they give a strong warm dye — the traditional colouring for eggs across eastern and central Europe, where they are wrapped around eggs with leaves and tied in cloth to print a pattern. They go into stock, into compost, into the bottom of a dye pot with iron to make a deeper brown.
The onion itself carries an old load of folk practice. Cut and left in a sickroom to draw off illness, which persists as internet advice despite having no basis; written on with names and set aside on St Thomas's Eve to see which sprouted first and so which suitor to take; peeled layer by layer in divination rhymes. The image of a thing with layers all the way down did a great deal of work in the folk imagination.
Craft uses the skins for protection and for absorbing — burnt after a difficult day, or included in a jar working where something needs to be taken away. It is a good example of a correspondence built out of an ordinary domestic act rather than a book.
Readings practitioners have offered, ordered by how many recognise them. Take what serves, leave the rest.
Carried forward
Nicholas Culpeper, The Complete Herbal (1653)
Culpeper writes that Mars owns onions, and that they have gotten this quality — to draw any corruption to them. The modern habit of leaving a cut onion out to absorb sickness is this idea, several centuries downstream, and it was never true.
Carried forward
Central and eastern European household practice
Eggs bound with leaves and onion skins, tied in cloth and boiled, come out patterned in deep russet. It is dyeing, printing and a seasonal rite at once, and it works reliably, which is more than most of this book can claim.
Credit what you carry. Much of this comes from living traditions, and some of it from traditions that are closed — held by particular peoples and not offered for general use. Where you know whose practice a reading came from, name them; where you don't, say that too.