Ivern, The Green Father

Creatures you control have Forestwalk

Whenever you tap a land for {g} mana, that land produces an additional {g}{g} mana

Daisy -- {3}{g}: Create a 6/6 creature token named "Daisy" that has Haste, Trample, and "When this creature leaves the battlefield, add {g}{g}{g} to your mana pool"

Your mana pool doesn't empty at the end of each of your turns