Relics from the original Naim logo?

Black puddings ?

Turntable warmers.

Not turntable sized, only 19-mm (3/4-inch) in diameter. Well hidden, disposable, yet common household objects, I had three pairs of them that I only noticed when doing some maintenance on my 22-year-old dwelling.

Toilet seat warmers?

Toilet seat washers?

Grommet Warmers ?

They're not warmers of any kind, but Graham and sjbabbey have nailed the household appliance from which these originated!

Aren't they the little washers that fit between the metal seat fittings and the China pan?

Rather than outside, think inside the box.

Used in the toilet tank, they are the nylon chain keepers that position the adjustable float between toilet handle and flapper valve. One above and one below the float.

Shown here in white:

Not in a standard UK toilet !!

Indeed. Chamber pots have no floats, chains or flapper valves

That reminds me of visits to my great-aunt in Clitheroe back in the '50s.  They had an outside toilet of a type I think is called a tipper toilet.  Basically a hole cut in a board over a bowl which would empty itself when full!  These youngsters know nothing ..,