If you put in your Two-Penny's Worth you add an opinion that could be regarded as virtually worthless. The phrase’s origin is in America, when the US Treasury issued two-cent, three-cent and twenty-cent coins in 1864. They were the first coins to bear the phrase “In God We Trust” and the two-cent coin, being the lowest in value, became used as a self-deprecating or modest way of offering an opinion. By the late 1800s “let me have my two cents' worth” was a standard prelude to offering suggestions. A person saying this and then offering an opinion that was later regarded as worthless could claim they had warned in advance it may have had a low value.