Poking around YouTube a bit, I stumbled upon an impressive performance of "Flower Fields" from Kirby's Epic Yarn by YouTube poster Raynald "Dekreme" Mirville.

You can find a few other performances of songs from the game on his list of YouTube uploads, as well as some other Nintendo music. But even more impressive, Dekreme has kindly penned and posted quality sheet music in PDF format. I've parsed and attempted to pound out a reasonable amount of amateur video game sheet music, and this is amongst the more accurate and legible I've seen. Since Kirby's Epic Yarn prominently features the piano, transcriptions are straightforward and can comprehensively cover the source material while still remaining playable.

My favorite song / sheet music of the bunch, "Secret Island", was actually transcribed by Will Buck, not Dekreme, and is especially good stuff.

While I haven't found any accompanying sheet music, I would be remiss if I didn't also mention the excellent rendition of "Weird Woods" by Joshua "Mercury" Cortese of Aussie-Nintendo.

So often the sheet music I find on the Internet is poorly laid out, inaccurate, or takes unwelcome artistic liberties. While imperfect sheet music is better than none, it's always nice to find quality renditions of video game songs you love.

If you're a casual pianist with discerning taste in sheet music, I also recommend Joseph Karam's authentic sheet music from the original Super Mario Bros.