I have found about 6-7 of these at various times on the floor in my kitchen. They are small and plastic, looked broken or snapped off on one end. I cannot figure out what it's from. It have checked cabinets, appliances, etc. Nothing. It looks like some kind of package was snapped open and this came off, but we haven't done that.
Do you have plastic freezer containers? If you drop them they break, often at the end.
Do you have any black plastic trash cans that might be chipping?
Sometimes these start breaking around the bottom or a peddle if it has one.
Do you have black handles on your stovetop (burners)? Our old stove, the knobs started breaking and the pieces looked similar to what you have here, only the old stove was white knobs.
This looks familiar! This looks like pieces of cookware(like pot handles) after long use and wear and tear they tend to chip away.
Check the handles on all of your frying pans and your cooking posts. I had had a few of them break after years of use. This looks like a piece that has broken off around the screw area on the handle.
Is it possible they are pieces of Drawer Glides? You know, the things inside the drawer openings that act as a slide area so drawers aren't sliding right on bare wood through the cabinet openings? OR, maybe a drawer stop/catch...check under the middle of the drawers.
If you have a cat it could be they've found bits of leftover construction or remodelling materials to play with. ^._.^