Golgari Germination

Whenever a nontoken creature you control dies, create a 1/1 green Saproling creature token.

Karn's Bastion

{T}: Add {C}.
{4}, {T}: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Plains

Sprout Swarm

Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.)
Buyback {3} (You may pay an additional {3} as you cast this spell. If you do, put this card into your hand as it resolves.)
Create a 1/1 green Saproling creature token.

Orzhov Basilica

Orzhov Basilica enters tapped.
When Orzhov Basilica enters, return a land you control to its owner's hand.
{T}: Add {W}{B}.

Fungus Frolic

Create two 1/1 green Saproling creature tokens. (Then exile this card. You may cast the creature later from exile.)

Brightcap Badger

Each Fungus and Saproling you control has "{T}: Add {G}."
At the beginning of your end step, create a 1/1 green Saproling creature token.

Brightcap Badger // Fungus Frolic

Command Tower

{T}: Add one mana of any color in your commander's color identity.

Fungal Sprouting

Create X 1/1 green Saproling creature tokens, where X is the greatest power among creatures you control.

Swamp

Utopia Mycon

At the beginning of your upkeep, put a spore counter on Utopia Mycon.
Remove three spore counters from Utopia Mycon: Create a 1/1 green Saproling creature token.
Sacrifice a Saproling: Add one mana of any color.

Ghave, Guru of Spores

Ghave, Guru of Spores enters with five +1/+1 counters on it.
{1}, Remove a +1/+1 counter from a creature you control: Create a 1/1 green Saproling creature token.
{1}, Sacrifice a creature: Put a +1/+1 counter on target creature.

Selesnya Sanctuary

Selesnya Sanctuary enters tapped.
When Selesnya Sanctuary enters, return a land you control to its owner's hand.
{T}: Add {G}{W}.

Temple of Plenty

Temple of Plenty enters tapped.
When Temple of Plenty enters, scry 1.
{T}: Add {G} or {W}.

Vitu-Ghazi, the City-Tree

{T}: Add {C}.
{2}{G}{W}, {T}: Create a 1/1 green Saproling creature token.

Forest

Sporecrown Thallid

Each other creature you control that's a Fungus or Saproling gets +1/+1.

Sporemound

Landfall — Whenever a land you control enters, create a 1/1 green Saproling creature token.

Temple of Malady

Temple of Malady enters tapped.
When Temple of Malady enters, scry 1.
{T}: Add {B} or {G}.

Golgari Rot Farm

Golgari Rot Farm enters tapped.
When Golgari Rot Farm enters, return a land you control to its owner's hand.
{T}: Add {B}{G}.

Aura Mutation

Destroy target enchantment. Create X 1/1 green Saproling creature tokens, where X is that enchantment's mana value.

Sporeweb Weaver

Reach, hexproof from blue
Whenever Sporeweb Weaver is dealt damage, you gain 1 life and create a 1/1 green Saproling creature token.

Temple of Silence

Temple of Silence enters tapped.
When Temple of Silence enters, scry 1.
{T}: Add {W} or {B}.