Start with high-confidence trivia & fun facts books, then narrow by subgenre or adjacent topics.
Don't Know Much About the Civil War
Kenneth C. Davis
The Official Quotable Doctor Who
Cavan Scott, Mark Wright
The Nitpicker's Guide for Next Generation Trekkers Volume 1
Phil Farrand
The Nitpicker's Guide for Classic Trekkers
New Jersey Curiosities
Peter Genovese
What They Never Told You About Boston
Walt Kelley
Phraseology
Barbara Ann Kipfer PhD, Barbara Ann Kipfer
The Hidden Magic of Walt Disney World Trivia
Susan Veness
Tiny New York
Suzi Siegel
What Did We Use Before Toilet Paper?
Andrew Thompson
True Facts That Sound Like Bull$#*t
Shane Carley
