From Pixelmon Wiki
A Yellow Apricorn is an Apricorn that can be cooked into a cooked Yellow Apricorn in a furnace. These cooked Yellow Apricorns can be used to make Poké Ball discs for Ultra Balls, Level Balls, Moon Balls, Friend Balls, Safari Balls, Fast Balls, and Nest Balls. Uncooked Yellow Apricorns are also used to craft certain decorative blocks.