Bee asked me in a comment when it was I first started writing poetry. I tried to answer her but it felt as if I was writing too much to leave in a response. So I promised to post my answer. The answer is I don't know. That is I don't know if you count juvenalia.
My mother claims my favorite book when I was a child was Robert Louis Stevenson's A Child's Garden of Verse. That may be why I bought it for my own kids when they were small.
My first success at poetry -- we're talking real juvenalia here -- came in the third grade. The Holy Name Catholic School newspaper published a poem I had written about my religious joy. I don't remember much except how it started.
I wish I were the little bell
That tinkles loud and clear
To tell the people kneeling down
That you are coming near.
That was it for poetry for a long time. When I was in the fourth or fifth grade I won an essay contest sponsored by the newspapers in Columbus. There were three winners from the city -- one for each paper -- and I was the youngest of the three. The essay was about why my father should be named father of the year, and the prize was three days and two nights in Washington DC at the Mayflower Hotel, including air fare, tickets for the All Star game, and fifty dollars pocket money. The editor of the Dispatch also arranged for a friend of his, the head of the transit company in DC, to give my father and me a personal tour of the city.
My family was not a literary family. The only books I recall being in the house until I was 11 were kids' picture books, Reader's Digest condensed novels, books about art, books about crafts, and scout books. My father was a boy scout leader. He also painted, worked with ceramics, did wood carvings, made things out of leather, and invented his own art media. He also taught ceramics at night in a studio on the north side of town. The one thing he didn't do was quit his day job.
I did go to the library and got books from school. At the library I would find juvenile sports novels. The kind where some bright and talented high school football player went to Small Time College because he needed to stay close to home and help the family by working in the five and ten. (They call them dollar stores now but five and tens were much better.) He makes the football team, has problems in school that weren't entirely his fault, and almost gets kicked off the team. Things always seemed to work out, though, and he'd make the team just in time to play so that Small Time College got it's biggest win ever against Humongous State University.
The books I got at school were mainly hagiography. The one I remember the most was called God's Teenager about the life of Dominic Savio who died at the age of fifteen. The biggest effect these books had on me was to make me do things like go to sleep at night wondering what it felt like to wear a hair shirt.
I continued writing little poems in the style of A Child's Garden of Verse and getting them published in the school paper and other similar venues. But I much preferred prose and studying math and history.
When I was 11 we moved into a house outside the city that had belonged to a professor friend of my father who had died. We got the furniture and the books. And I was hooked on books.