Plains

Heliod's Pilgrim

When Heliod's Pilgrim enters the battlefield, you may search your library for an Aura card, reveal it, put it into your hand, then shuffle.

Soul Warden

Whenever another creature enters the battlefield, you gain 1 life.

Presence of Gond

Enchant creature
Enchanted creature has "{T}: Create a 1/1 green Elf Warrior creature token."

Llanowar Elves

Midnight Guard

Whenever another creature enters the battlefield, untap Midnight Guard.

Mountain

Congregation at Dawn

Search your library for up to three creature cards, reveal them, then shuffle and put those cards on top in any order.

Forest

Goldnight Commander

Whenever another creature enters the battlefield under your control, creatures you control get +1/+1 until end of turn.

Splinter Twin

Enchant creature
Enchanted creature has "{T}: Create a token that's a copy of this creature, except it has haste. Exile that token at the beginning of the next end step."

Ogre Battledriver

Whenever another creature enters the battlefield under your control, that creature gets +2/+0 and gains haste until end of turn. (It can attack and {T} this turn.)

Cultivate

Search your library for up to two basic land cards, reveal those cards, put one onto the battlefield tapped and the other into your hand, then shuffle.

Nature's Claim

Destroy target artifact or enchantment. Its controller gains 4 life.

Evolving Wilds

{T}, Sacrifice Evolving Wilds: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Life and Limb

All Forests and all Saprolings are 1/1 green Saproling creatures and Forest lands in addition to their other types. (They're affected by summoning sickness.)

Impact Tremors

Whenever a creature enters the battlefield under your control, Impact Tremors deals 1 damage to each opponent.

Scute Swarm

Landfall — Whenever a land enters the battlefield under your control, create a 1/1 green Insect creature token. If you control six or more lands, create a token that's a copy of Scute Swarm instead.

Sunstrike Legionnaire

Sunstrike Legionnaire doesn't untap during your untap step.
Whenever another creature enters the battlefield, untap Sunstrike Legionnaire.
{T}: Tap target creature with mana value 3 or less.

Nature's Lore

Search your library for a Forest card, put that card onto the battlefield, then shuffle.

Sporemound

Landfall — Whenever a land enters the battlefield under your control, create a 1/1 green Saproling creature token.