I had to remove my master cylinder for overhaul and after I put it back I found a little spring on the floor. Where the heck it came from, looks broken, too.

 

Looks like a brake pedal return spring. Did you pull the pivot pin on the pedal in the process of changing the master?

 

That's what is confusing, I did not pull the pivot pin. Anyhow, the clutch pedal feels not the same, so it must have been from clutch pedal. Methinks the assembly is from 1988- manual transmission car (inline 6). I wonder if this spring is sold somewhere ...

 

Not local to you but you could try here. As you can see l think your spring is missing the tails.

 

Thanks, with little detective work I started at Jagdaim and reached Terry's part C25506 ... looks similar.