Polished buttons

Polished buttons are obtained by polishing regular buttons (use right click on them) and when polished you receive 5 Crafting experience.

One may get the buttons by pickpocketing H.A.M. members, killing H.A.M Guards, digging in the Level-1, Level-2 or Level-3 digsite east of Varrock, opening Ogre coffins, or the Fishing Trawler.

They are used in the Animal Magnetism quest.

Although in the Crafting skill book it doesn't say Members only, buttons can't be polished by free players since they are a Members object. However, the resulting polished buttons are not.

Use in arbitrage scam
Players would sometimes trick other players, usually non-members, into thinking the item was rare, and other players would sometimes trade up to 100,000 coins for them. Because of this, Jagex made them untradeable in the 20 November 2007 update.

Polished buttons