Maybe some old tech or gadget you have laying around that isn’t worth much and you’re unlikely to user/sell/repurpose. Just make sure to remove any kind of battery, and wrap the device in paper, then plastic to minimize chance of corrosion damage and mess from plasticizers breaking down

A construction/utility worker in 50–100 years may get a kick out of seeing a midrange smartphone from 2010 the same way I’d be thrilled to find a cheap trypewriter or electric clothes iron from 50+ years ago. Mundane things don’t tend to get intentionally preserved, so it’s fun when you find one.