Put your two cents in

To put your two cents in is to give your opinion. A cent is the smallest coin of American money, and so the expression has a modest, humble feeling. Here are some examples:

After listening to the others for a long time, she finally decided to put her two cents in.

"Mary, you know a lot about this subject, so why don't you put your two cents in?"

"Well, you may not agree with me, but I want to put my two cents in before we make a decision."