There are many items that we can feed chocobo. Such as Gyshal Green (ギサールの野菜) (and other green), Choconamin (チョコナミン) etc
For gyshal green, you can buy a seed from the man that sell item in front of campus farm. (last item in his shop) Then plant it in Salala's (サララ) garden. The next 6 hrs you will get gyshal green.
For Choconamin, go to 森の宿場ヤクト (north east of forest jagd -ヤクトの森-). There is npc that you can trade Chocobodake (チョコボダケ) ×8 and Namekuji Sweet (なめくじスイーツ)×6 to Choconamin
チョコボダケ - found in jagd forest field
なめくじスイーツ - drop from Rafflesia (ラフレシア) in jagd forest.
For gyshal green, you can buy a seed from the man that sell item in front of campus farm. (last item in his shop) Then plant it in Salala's (サララ) garden. The next 6 hrs you will get gyshal green.
For Choconamin, go to 森の宿場ヤクト (north east of forest jagd -ヤクトの森-). There is npc that you can trade Chocobodake (チョコボダケ) ×8 and Namekuji Sweet (なめくじスイーツ)×6 to Choconamin
チョコボダケ - found in jagd forest field
なめくじスイーツ - drop from Rafflesia (ラフレシア) in jagd forest.