There is a children's book called 100 Hungry Ants about an army of ants marching towards a picnic. As they are marching, their tummies make hungry sounds that keep getting progressively louder as the book continues.
Black Dagger Brotherhood has a few examples as well—since Ward's vampires need food as well as blood. Phury's is most frequent at first; being a whacked-out drug addict he frequently forgets to eat.
In the Captain Marvel novel Liberation Run, Jessica Drew pesters Carol Danvers to pull rank so they can get seated at a restaurant with a ridiculously long line. Despite being tempted by her growling stomach, Carol refuses to abuse her superhero status for something so minor and petty, much to Jess' annoyance.
In the DC Super Hero Girls novel Harley Quinn at Super Hero High, Harley's stomach growls very loudly while looking for Mad Hatter, which reminds her that she hasn't eaten lunch.
In Dinoverse, this accompanies the first time the kids-in-dinosaur-bodies feel hunger.
There's a book called Grumble! Rumble! where the character Little Roo thinks there's a monster in her tummy.
At the end of Junie B. Jones is a Party Animal, Junie's stomach lets out a loud, hungry growl during the car trip home since she wasn't able to eat much at Lucille's house after causing a scene at breakfast. Luckily for her, she's got pancakes waiting for her at her grandma's.
In the My Little Pony book "Applejack and the Honest-To-Goodness Switcheroo", the smell of Granny Smith's delicious cooking makes Applejack's tummy rumble. Tempted as she is to eat though, she refuses until her siblings come home, since she's a firm believer in eating together as a family.
This tends to happen to Nancy herself in later books. In The E-Mail Mystery, her stomach rumbles when she returns home after working up an appetite on a run and is greeted by the smell of her housekeeper Hannah's delicious blueberry pancakes. Nancy's stomach also growls in anticipation of all the delicious vegetarian food she sees at a fundraising dinner in The Clue at Black Creek Farm, only for things to go off the rails when guests begin getting violently sick due to the food being mysteriously laced with E. Coli, kicking off the plot of the book.
At the very beginning of Where's Nancy, an impatient George's belly starts growling loudly while she and Bess are waiting for Nancy at a restaurant, until she loses her patience and decides to eat without her. This is the first sign that something bad happened to Nancy, and it becomes clear after she keeps missing other important events later that she's gone missing.
Happens throughout the Shivers title: "Curse of the New Kid"; every time Luke got bullied, his stomach would roil increasingly strong, loud and painfully, and something terrible happened to the person picking on him.
In the third book of the Spellsinger series, Roseroar says "Ah've got a bellyfull of thunder" when asked if she's hungry.
In a children’s book called Starly the Hungry Unicorn, the titular character, Starly is personified in this trope. Her tummy growls repeatedly throughout the book as she searches for food, which is each time dictated as “Grumble, grumble, grumble.”
In an obscure Christian thriller called Such Sweet Sorrows, a cop named Danny gets this cause he's hungry (he had no breakfast)
In the book "Word World: Bear The Pizza Tree", Bear was woken up by the sound of her tummy rumbling.
Jaina Proudmoore's stomach rumbles in the World of Warcraft novel "Arthas: Rise of the Lich King" when she gets hungry at the Dalaran gardens in the beginning of Chapter 6.
Thanks to being tempted by a nearby bakery and not having eaten in a while, Alia's stomach rumbles while she and Diana try to steal a car shortly after arriving in New York in Wonder Woman: Warbringer.
Gas and/or gut trouble
An anonymous limerick:
I sat next to the Duchess at tea. It was just as I feared it would be. Her rumblings abdominal Were simply abominable And everyone thought it was me!
In Postman Pat's Sleepy Days, a book based on Postman Pat, Miss Hubbard suggests that Pat have a glass of rhubarb wine to help him sleep. That night, Pat's rumbling stomach wakes both him and his wife Sara.
In World of Warcraft: Cycle of Hatred, Jaina Proudmoore's stomach is said to rumble as a constant side-effect of her teleportation spell, with her most recent use causing an incredibly noisy rumble due to the undigested jerky in her belly, which moments later she past through the effect.
