Hoppip

Whenever a Forest or Plains enters the battlefield under your control, you may return Hoppip from your graveyard to the battlefield.
Whenever Hoppip enters the battlefield under your control, it explores. (Reveal the top card of your library. Put that card into your hand if it's a land. Otherwise, put a +1/+1 counter on this creature, then put the card back or put it into your graveyard.)
Flying.