Copper Myr

Tree of Tales

Leaden Myr

Palladium Myr

Dryad Arbor

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

Darksteel Citadel

Yavimaya, Cradle of Growth

Each land is a Forest in addition to its other land types.

Forest

Rendmaw, Creaking Nest

Menace, reach
When Rendmaw, Creaking Nest enters and whenever you play a card with two or more card types, each player creates a tapped 2/2 black Bird creature token with flying. The tokens are goaded for the rest of the game. (They attack each combat if able and attack a player other than you if able.)

Urborg, Tomb of Yawgmoth

Each land is a Swamp in addition to its other land types.

Vault of Whispers

Swamp

Valgavoth's Lair

Hexproof
Valgavoth's Lair enters tapped. As it enters, choose a color.
{T}: Add one mana of the chosen color.