So let's take a look at each:
"E pluribus unum"
Surely you have heard of this expression and maybe you know what it means. Just in case you don't, it is Latin for "One out of many" or "One among many". This expression used to be the motto of the United States of American, adopted by an act of Congress in 1782. (It is also the motto for the biggest soccer (or football) club in Portugal, the great BENFICA.) The expression was chosen at the time to represent the union of the various states of the United States, and today it has evolved to represent the idea of the melting pot in the U.S.A., or the union of various races, religions, languages, and ancestries.
"In God We Trust"
In 1956 Congress passed act adopting "In God We Trust" as the official motto of the United States, leaving behind "In pluribus unum" (though it still can be found on our currency...). The president at that time was Dwight Eisenhower. "In God We Trust" first appeared on paper currency in 1957. The phrase was taken from the "Star-Spangled Banner" (the national anthem), which was written by a 35-year-old lawyer/amateur poet named Francis Scott Key after witnessing the bombardment of Fort McHenry during the War of 1812. There is controversy surrounding this motto, as there exists a separation of the Church and the State in the U.S.A. (This is a conversation that regularly comes up among Americans...even as teenagers, we would discuss this.) However, it continues to be the official motto of the U.S.A., supported and upheld legally as an act of Congress.
That's it for today. I hope you liked the history lesson!