A small mod which gives by deafault gives a hoof at level 5, wax quail at level 10 and a feather at level 15.
The mod requires the use of the internal item names which can be found on the R2Wiki
Once the mod has been launched the config can be used to change what level or item.
It must be formated like [Level]-[ItemName] seperated by a ',':
"5-JumpBoost,15-Feather"
The above will spawn a Wax Quail at level 5, and a Hopoo Feather at level 15