One of my favorites is
Fire and Ice by Robert frost
Some say the world will end in fire,
Some say in ice.
From what I've tasted of desire
I hold with those who favor fire.
But if it had to perish twice,
I think I know enough of hate
To say that for destruction ice
Is also great
And would suffice.
No I haven't shared it with the kids

I donno why I liked it, I read it in 6th or 7th grade and have liked it since
My other favorites would be most of Shel Silverstein, from Where the Sidewalk Ends, The Giving Tree and A Light in the Attic