What does "ready to quarrel over a truffle mean"?Its in Act 2 scene 4 of Romeo and Juliet.

I do not believe that this phrase appears in Romeo and Juliet at all, and I particularly do not think it appears in this scene.

In this scene, the character Peter uses the word "quarrel" but he does not use it in anything like the phrase you mention.

I thought that maybe you were referring to a part in Act III, Scene 1 where Mercutio is telling Benvolio that Benvolio is always ready to quarrel.  Your phrase would fit there, but it's not there.

I would think what the phrase would mean is that the person is ready to fight over any little thing.  It would mean that even more if it were "ready to quarrel over a trifle."