He gave me a piece of his mind. = He stated his views to me very bluntly.
It's more usual that the speaker refers to himself:
I gave him a piece of his mind.: I told him (angrily) what I thought of him and his actions (i.e. my comments were highly unfavourable!)
There was a meeting of
ourminds. = We were all on theof a same mindsmind. = We all had the same opinion.
Student or Learner