Kirby's Return to Dream Land
The first appearance of score coins is in the Challenge Stages playable from within the Lor Starcutter. They come in silver and gold varieties, worth 100 and 1000 points respectively. They resemble round Roman-style coins, but bear stars on them instead of faces.
Collecting every coin in the stage confers upon Kirby an additional bonus.
Kirby's Dream Collection Special Edition
One thing to note is that during the Magolor Races, Magolor is capable of picking up these coins as well. If he gets them, they will become unavailable to Kirby.
Kirby: Triple Deluxe and Dedede's Drum Dash Deluxe
In both the original Dedede's Drum Dash and its deluxe version, Musical Coins can be collected along the path, and a bonus is conferred if all of them are collected in a given stage. Here, bronze coins are worth 50, silver 200, and gold 500. Exclusive to Dedede's Drum Dash Deluxe are numbered coins which need to be collected in the correct order. Each of these are worth 100 points save for the last one, worth 800.
Kirby: Planet Robobot and Kirby's Blowout Blast
In both Kirby 3D Rumble and Kirby's Blowout Blast, coins are scattered across the stage, and earn points when collected. Unlike the coins in other titles, the ones found here are squarish, similar to the cuboid nature of the stages themselves. Coins here come in three types; bronze are worth 100 points, silver 500 points, and gold 3000 points.