At the Online Nature Collectors’s Swap Shop, you can trade chores you do at home for small rock and mineral specimens that have been rounded, smoothed, and polished in rock tumblers.
This video shows a rock tumbler in action: https://www.youtube.com/watch?v=PZO-lgeTBpI
Here’s a web page that tells how rock tumblers work: https://geology.com/rock-tumblers/
The following web page can help you identify the polished rocks you traded for at the Swap Shop. (But rocks are really variable, so do no be surprised if you cannot identify every tumbled rock.)
RockTumbler.com Picture Guide to Polished Rocks and Tumbled Stones: https://rocktumbler.com/polished-stones/
This web page has photos and information about dozens of polished rocks, plus a link to a gemstone identification chart that you can download and print!