Egg Marks the Spot (Skunk & Badger #2) by Amy Timberlake

From Algonquin Books:

When roommates Skunk and Badger head out on a rock-finding expedition, they find surprises behind every boulder in this follow-up to the bestselling, award-winning Skunk and Badger.

“X Marks the Spot!”

Buried in the heart of every animal is a secret treasure. For rock scientist Badger, it’s the Spider Eye Agate he found as a cub, stolen years ago by his crafty cousin, Fisher. For Badger’s roommate, Skunk, the treasure is Sundays with the New Yak Times Book Review. When an old acquaintance, Mr. G. Hedgehog, announces his plan to come for the Book Review as soon as it thumps on the doorstep, Skunk decides an adventure will solve Badger’s problems as well as his own. Surprisingly, Badger agrees. Together
they set off on an agate-finding expedition at Badger’s favorite spot on Endless Lake.

But all is not as it seems at Campsite #5. Fisher appears unexpectedly. Then a chicken arrives who seems intent on staying. Something is up!

Indeed!

Secrets, betrayals, lies

. . . and a luminous, late-Jurassic prize.
 
In a volume that includes full-color plates and additional black-and-white illustrations by Caldecott medalist Jon Klassen, Newbery Honor author Amy Timberlake takes readers on a second adventure in the new series reviewers have called an instant classic, with comparisons to Frog and Toad, Winnie-the-Pooh, and The Wind in the Willows.