People are being invited to dig out their hidden treasures and take them along to museums and galleries across England for an expert opinion.
Former Rolling Stone Bill Wyman launched Fabulous Finds Day at the Museum of London on Saturday.
Curators and experts from the Portable Antiquities Scheme will examine anything from coins and fossils to retro toys picked up at car boot sales.
The event signals the start of Museums and Galleries Month.
Nine museums across England are taking part in the event and objects brought in will form part of an online exhibition at www.24hourmuseum.org.uk.
Fabulous Finds Day is designed to encourage families and young people to visit their local museums and galleries.