The first mention of the Trinity

One of the main tenants of the Christian faith is that of the Trinity, the Father, the Son, and the Holy Ghost. Yet I've noticed it to be a subject a lot struggle with. "For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life." (John 3:16)

People have questioned the Trinity saying there's no recollection of Jesus in the Old Testament, but I can think of two examples right off the top of my head. The first is that of Melchisedec in Hebrews 7:1-10, and Genesis 14:18-20 and Psalm 110:4-5. According to the Scriptures, I believe Jesus was the aforementioned Melchisedec.

However, the Trinity is mentioned before Genesis 14, it is mentioned in the garden of Eden!
Genesis 3:5
"For God doth know that in the day ye eat thereof, then your eyes shall be opened, and ye shall be as gods, knowing good and evil."

"and ye shall be as gods"-
initially my thought was the frame of thinking that the LDS church believes, that everyone will be gods in their own right, but this is not the case in this passage. Looking further, the word used for this is "'elohiym ", used in the singular- plural intensive tense, defined as "the (true) God", which is uppercase "G:, not lowercase- which, makes a BIG difference!

Looking deeper in verse 22:
"And the LORD God said, Behold, the man is become as one of us, to know good and evil: and now, lest he put forth his hand, and take also of the tree of life, and eat, and live for ever"

"one of US" = there are THREE in the Godhead! If God was a singular entity, then this would have definitely been worded differently, because God is not the author of confusion.

It amazes me at the many little nuggets of information we read in the bible, and miss them for years then all of a sudden the Lord opens our eyes to a little more wisdom as we grow and mature in our faith and walks with Him. I have read that passage countless times but that never struck out at me until last week. What a blessing to have him confirm one more time that yes, he is in control and yes, he has us covered in (most) all of the answers to the questions we have. Praise the Lord!!