Phraseology

Twice today I've come across the phrase "say your piece". For some reason it never occurred to me that the word was "piece" as I'd always assumed it to be "say your peace". Fortunately, I'm not the only one who makes this mistake. However, the correct answer is here.

I think the confusion comes from these two phrases: "peace of mind" vs. "I want to give you a piece of my mind". For whatever reason I assumed that when you said your "peace" that you were getting something off your chest so you could have "peace of mind", not to give someone a "piece of your mind" which seems unnecessarily antagonistic in most cases when this phrase is used.

Anyone else have a take on this? What phrases have you misheard in the past?