Nestled in a north Georgia forest, over 4,000 classic cars decorate 32 acres that have been turned into a junkyard museum. Owner Walter Dean Lewis’ parents started the business in 1931 as a general store that also sold auto parts. Lewis grew the collection, which had just 40 cars in the ’70s, over time. “The only thing I ever knew was cars and trucks,” Lewis says. “I like to say I work for tomorrow, always thinking about the future. Someday they would be valuable.” Lewis stopped selling parts about six years ago, soon after realizing he could sustain the business...