They look like blanks for the British decimal 50 pence coin. The weight seems about right (8g). The diameter should be 27.3 mm ─ have you checked it?
One thing that makes me doubt this identification is the metal, but UK collectors, hopefully, will come to your assistance. By the way, are they magnetic?
So, they are not 50-pence blanks. But are they coin blanks at all?
An argument in favor is that it's seven-sided. Odd numbers of sides are preferred for coins because the diameter is the same everywhere you measure it, unlike even-numbered sides. This is important if you want coins to be used in vending machines.
An argument against, it seems to me, is that the blanks are not entirely ready for being used as coin planchets. One can see from which side they were cut, i.e. the side with the more rounded edges. If they were coin planchets, I would expect that the edges on both sides to be identical, so that the minting process is not affected in any way. This is just a hypothesis; perhaps someone knows more about this that I do.
Still, seven-sided is pretty uncommon for coins. You could try to google "seven-sided coin" and see what you get beside the UK 50 pence coin, and compare with your diameter.
