The Academy of American Poets has a wonderful website, Poets.org, that I often go to if I'm looking for a group of poems about a specific theme. It's super-easy to navigate:
So there you go - lots of poems about shoes, aliens, shark week. Also, as you can see, there's a "For Teens" page of poems. Under "Life and Leisure," there's a "childhood" page of poems, and under "Family and People," there are poem pages for "parenting," "daughters," and "sons."
Even BETTER, at least for our investigative purposes, is the Poetry Foundation's website, which has a similar categories function, which they call the "Poetry Tool."
(I made the blue circles)
As you can see, there is a whole section roped off for "Children's."
There are tons of great nooks and crannies on both of these organization's websites - for example, I stumbled upon "Ten Poems to Get You Through Science Class," which I would have loooved to use as a resource while I was growing up. If our lockers were any bigger, I probably would have also appreciated "Ten Poems to Read When You Get Stuffed in a Locker."
Anyway, have fun with these websites!