Leafkin Druid

{T}: Add {G}. If you control four or more creatures, add {G}{G} instead.

Elvish Mystic

Incubation Druid

{T}: Add one mana of any type that a land you control could produce. If Incubation Druid has a +1/+1 counter on it, add three mana of that type instead.
{3}{G}{G}: Adapt 3. (If this creature has no +1/+1 counters on it, put three +1/+1 counters on it.)

Elvish Harbinger

When Elvish Harbinger enters, you may search your library for an Elf card, reveal it, then shuffle and put that card on top.
{T}: Add one mana of any color.

Birds of Paradise

Elfhame Druid

{T}: Add {G}.
{T}: Add {G}{G}. Spend this mana only to cast kicked spells.

Gilded Goose

Flying
When Gilded Goose enters, create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this artifact: You gain 3 life.")
{1}{G}, {T}: Create a Food token.
{T}, Sacrifice a Food: Add one mana of any color.

Overgrown Battlement

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

Marwyn, the Nurturer

Whenever another Elf you control enters, put a +1/+1 counter on Marwyn, the Nurturer.
{T}: Add an amount of {G} equal to Marwyn's power.

Sylvan Caryatid

Defender, hexproof
{T}: Add one mana of any color.

Accomplished Alchemist

{T}: Add one mana of any color.
{T}: Add X mana of any one color, where X is the amount of life you gained this turn.

Gyre Sage

Evolve (Whenever a creature you control enters, if that creature has greater power or toughness than this creature, put a +1/+1 counter on this creature.)
{T}: Add {G} for each +1/+1 counter on Gyre Sage.

Druid of the Cowl

Vine Trellis

Defender (This creature can't attack.)
{T}: Add {G}.

Ulvenwald Abomination

Ulvenwald Captive

Defender
{T}: Add {G}.
{5}{G}{G}: Transform Ulvenwald Captive.

Ulvenwald Captive // Ulvenwald Abomination

Golden Hind

Delighted Halfling

{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast a legendary spell, and that spell can't be countered.

Saruli Caretaker

Defender
{T}, Tap an untapped creature you control: Add one mana of any color.

Llanowar Tribe

Orochi Leafcaller

Viridian Joiner

{T}: Add an amount of {G} equal to Viridian Joiner's power.

Llanowar Elves

Leaf Gilder

Karametra's Acolyte

{T}: Add an amount of {G} equal to your devotion to green. (Each {G} in the mana costs of permanents you control counts toward your devotion to green.)

Canopy Tactician

Other Elves you control get +1/+1.
{T}: Add {G}{G}{G}.

Priest of Titania

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

Elvish Archdruid

Other Elf creatures you control get +1/+1.
{T}: Add {G} for each Elf you control.

Sol Ring

Circle of Dreams Druid

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

Fyndhorn Elves

Devoted Druid

{T}: Add {G}.
Put a -1/-1 counter on Devoted Druid: Untap Devoted Druid.

Orochi Merge-Keeper

{T}: Add {G}.
As long as Orochi Merge-Keeper is modified, it has "{T}: Add {G}{G}." (Equipment, Auras you control, and counters are modifications.)