I found them in a lot of vintage darning yarn I got from an Etsy seller.

I assume they have something to do with sewing, darning, or mending given the lot they were in. There's a tiny hole through the ridge on the top.

And the edges are all scalloped.

They're pretty heavy, possibly even tempered glass or heavy plastic? idk.

/squints

I have no clue

are they flat on one side? if they're heavy, they might just be some sort of decorative fabric weight, but I can't tell if they're flat or round

One side has a very thin, flat ridge but they're both pretty small. I don't think they'd be very useful fabric weights. XD

My SIL said maybe they're for making pom poms or tassels, but she didn't know either.

you said they were heavy, so I was going off that. I've got a set that look like really heavy versions of those little glass rocks that go in plant pots

Yeah sorry, I meant heavy for their size. They're weighty but very small.

ooh, pom-pom makers seems possible!

hmm
toggle buttons?
the hole's in the right place/orientation

orrrr possibly some kind of bobbin/thread winder for a darning loom, since the rest of the lot was darning supplies

Yeah my brain's going buttons

Or the bobbin, yeah, that was the word I couldn't come up with

Ooh, a bobbin winder sounds like a possibility. It does look like you could wind thread around it. I've never used a darning loom so I don't know what you'd need with it.

This is my first time trying hand darning. I bought this batch since it seemed like a good way to start off my collection of darning thread with the basic colors.

they're lil tiny looms for darning flat sections

a lot of people use them for doing conspicuous mends

i mostly see them used with tapestry needles, but it's not a section of the craft world i'm deep into so idk the little details

Oh wow, I would never have guessed that! How cool!

Thank you for solving the mystery!

assuming it is solved!

anyway, yw

love a good craft mystery