Concrete poetry is defined as “verse that emphasizes nonlinguistic elements in its meaning”—which is a fancy way of saying that the words of a concrete poem are structured around a shape, a concept, or a particular constraint.
The acrostic poem is one such example, and the rule is pretty simple! When spelled vertically, the first letters of each line should form the title of your poem.
Here’s a favorite example from Robert Yehling:
Upon a glade of sun-sculpted
Pine forest, rooted in stone,
Layers of my bark peel away,
Inviting a softer surface to emerge. I climb
Far into the sky, following an eagle’s current
To the sun–
I melt into my sculptor...
Nestled by Her vision, I hear a new call:
"Go back to seed, and I will bring you Home."
Now you try. Write a poem, with the vertical first letters forming your title, as Gabriel Goodwin