I don't suppose anyone can tell me what either of these thingies are for?
Both are roughly 1/4" in shaft size. The one on the left, with the thread, has three protruding "nipples" on the underside of the head, while the one on the right has no thread and its surfaces are completely smooth. There are no "holes" for a screw driver and both are smooth circles at the "head" so no spanner either.
They came out of a big mixed box of bolts and screws that a mate gave to me so I've got not context at all as to where they would have been used. I may have said that they were feet for something, but they're both pretty small, so I doubt it.