Start with high-confidence word games books, then narrow by subgenre or adjacent topics.
Mental Magic
Martin Gardner
Gross Me Out Mad Libs
Gabriella DeGennaro
The Original #1 Mad Libs
Roger Price, Leonard Stern
Goofy Mad Libs
Super Silly Mad Libs Junior
Roger Price
Vacation Fun Mad Libs
Sleepover Party Mad Libs
Slam Dunk Mad Libs
Mad Libs on the Road
Dinosaur Mad Libs
Game Over! Mad Libs
Brandon T. Snider
Little Skill Seekers: Word Searches
Scholastic
Learn to Read: Sight Words Storybook
Kimberly Ann Kiedrowski
Ultimate Puzzle Challenge!
Highlights, Highlights for Children