Oodles of spare change discovered under the couch probably won't be the most valuable thing you unearth during spring cleaning.
Plenty of valuable items may be collecting dust in junk drawers and closets, from gently worn sweaters to outgrown skis and discarded smartphones—adding up to potentially hundreds of dollars in unclaimed cash.
"It's unbelievable what things are worth," said Mary Hunt, founder of DebtProofLiving.com. She recently rediscovered an old box of Teenage Mutant Ninja Turtles cereal saved for nostalgia and saw similar listings on eBay that have topped $45 in bids.
Even items that seem like junk—used printer cartridges, broken china—may have some value, said Trae Bodge, senior lifestyle editor at RetailMeNot.com. Sites like InkRecycling.org buy the former for a few bucks apiece, and the latter can be sold as craft materials on Etsy. "You would think people aren't interested in those things, but they are," she said.
Sales can take more effort than a fast yard sale, but the payoff can be substantial, particularly in these eight categories:
—By CNBC's Kelli B. Grant
Posted 4 Apri—l 2014