Gaea's Cradle

{T}: Add {G} for each creature you control.

Savannah

Dryad Arbor

(Dryad Arbor isn't a spell, it's affected by summoning sickness, and it has "{T}: Add {G}.")

Path to Exile

Exile target creature. Its controller may search their library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Squirrel Wrangler

{1}{G}, Sacrifice a land: Create two 1/1 green Squirrel creature tokens.
{1}{G}, Sacrifice a land: Squirrel creatures get +1/+1 until end of turn.

Silklash Spider

Reach
{X}{G}{G}: Silklash Spider deals X damage to each creature with flying.

Green Sun's Zenith

Search your library for a green creature card with mana value X or less, put it onto the battlefield, then shuffle. Shuffle Green Sun's Zenith into its owner's library.

Mirror Entity

Changeling (This card is every creature type.)
{X}: Until end of turn, creatures you control have base power and toughness X/X and gain all creature types.

Parallel Evolution

For each creature token on the battlefield, its controller creates a token that's a copy of that creature.
Flashback {4}{G}{G}{G} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Overrun

Creatures you control get +3/+3 and gain trample until end of turn. (Each of those creatures can deal excess combat damage to the player or planeswalker it's attacking.)

Forest

Squirrel Mob

Squirrel Mob gets +1/+1 for each other Squirrel on the battlefield.

Chatter of the Squirrel

Create a 1/1 green Squirrel creature token.
Flashback {1}{G} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Tormod's Crypt

{T}, Sacrifice Tormod's Crypt: Exile target player's graveyard.

Swords to Plowshares

Exile target creature. Its controller gains life equal to its power.

Biorhythm

Each player's life total becomes the number of creatures they control.

Coat of Arms

Each creature gets +1/+1 for each other creature on the battlefield that shares at least one creature type with it. (For example, if two Goblin Warriors and a Goblin Shaman are on the battlefield, each gets +2/+2.)

Berserk

Cast this spell only before the combat damage step.
Target creature gains trample and gets +X/+0 until end of turn, where X is its power. At the beginning of the next end step, destroy that creature if it attacked this turn.

Llanowar Elves

Deranged Hermit

Echo {3}{G}{G} (At the beginning of your upkeep, if this came under your control since the beginning of your last upkeep, sacrifice it unless you pay its echo cost.)
When Deranged Hermit enters, create four 1/1 green Squirrel creature tokens.
Squirrel creatures get +1/+1.

Priest of Titania

{T}: Add {G} for each Elf on the battlefield.

Altar of Dementia

Sacrifice a creature: Target player mills cards equal to the sacrificed creature's power.