Have

Wirewood Channeler

{T}: Add X mana of any one color, where X is the number of Elves on the battlefield.

Farseek

Search your library for a Plains, Island, Swamp, or Mountain card, put it onto the battlefield tapped, then shuffle.

Don't Have

Boreal Druid

Circle of Dreams Druid

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

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.

Elvish Guidance

Enchant land
Whenever enchanted land is tapped for mana, its controller adds an additional {G} for each Elf on the battlefield.

Druids' Repository

Whenever a creature you control attacks, put a charge counter on Druids' Repository.
Remove a charge counter from Druids' Repository: Add one mana of any color.

Elvish Mystic

Llanowar Elves

Priest of Titania

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

Quirion Elves

As Quirion Elves enters, choose a color.
{T}: Add {G}.
{T}: Add one mana of the chosen color.

Llanowar Tribe

Heritage Druid

Tap three untapped Elves you control: Add {G}{G}{G}.

Fyndhorn Elves

Arbor Elf

Lathril, Blade of the Elves

Menace (This creature can't be blocked except by two or more creatures.)
Whenever Lathril deals combat damage to a player, create that many 1/1 green Elf Warrior creature tokens.
{T}, Tap ten untapped Elves you control: Each opponent loses 10 life and you gain 10 life.

Canopy Tactician

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

Elves of Deep Shadow

{T}: Add {B}. Elves of Deep Shadow deals 1 damage to you.

Joraga Treespeaker

Level up {1}{G} ({1}{G}: Put a level counter on this. Level up only as a sorcery.)
LEVEL 1-4
1/2
{T}: Add {G}{G}.
LEVEL 5+
1/4
Elves you control have "{T}: Add {G}{G}."

Birchlore Rangers

Tap two untapped Elves you control: Add one mana of any color.
Morph {G} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)

Elvish Archdruid

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