I love onomatopoeia. I can't spell it. But I love it. Often when I'm singing songs to Maya, I'll change words to their sounds just for fun. For example, we sing a song when we're getting dressed to the tune of "Mama's Little Baby Loves..." that goes, "Baby put your shirt on, shirt on, shirt on. Baby put your shirt on, 1...2...3." There are often three snaps on onesies, so I change it to "Baby put your shirt on, snap...snap...snap." Or those pajamas with a long zipper and a snap at the top, "Baby put your jammies on, zip...zip...snap."
Hop! Plop!, by Corey Rosen Schwartz and Tali Klein and illustrated by Olivier Dunrea, is all about the onomatopoeia. Mouse and elephant are bored, so they go to the playground. When they get on the seesaw, Mouse goes "HOP! PLOP! BOOM! BOP!" onto the ground.
Elephant gives mouse a push on the swing, "SWING! WHIZ! FLING! DING!" around and around until he's wrapped around the bar. The whirlybird comes to a similar disappointing end.
Mouse decides that all the rides in the playground are broken. But Elephant has a great idea. He crouches down to make a slide with his trunk, "YEE-OW! SLIDE! GLIDE! WHAT A RIDE!" Mouse declares that Elephant is his favorite.
When you're reading, you need to do a good job with those bold-type words to really understand the illustrations. I think you'll have a pretty good time.