You control a nontoken Saproling and/or creature with changeling.
Steps
Activate Pallid Mycoderm's second ability by sacrificing a nontoken Saproling or creature with changeling.
When the creature dies, Yedora triggers, returning the creature from your graveyard to the battlefield face down as a Forest land and as a 1/1 Saproling due to Life and Limb.
Resolve the Pallid Mycoderm ability, giving Saprolings and Fungi you control +1/+1 until end of turn.
Repeat.
Results
Infinite death triggers.
Infinite ETB.
Infinite landfall triggers.
Infinite LTB.
Infinitely large Saprolings and Fungi you control until end of turn.