Their favorite place in all of Ravnica was still the glade where they first met.

Yeva, Nature's Herald

Flash (You may cast this spell any time you could cast an instant.)
You may cast green creature spells as though they had flash.

"I can call an army to my side in the blink of an eye. Best not blink."

Ravnica Remastered

Flash
You may cast green creature spells as though they had flash.

Secret Lair Drop

Duel Decks: Elves vs. Inventors

Magic 2013

Flash (You may cast this spell any time you could cast an instant.)
You may cast green creature cards as though they had flash.

Yeva's ability applies to green creature cards in any zone, provided something is allowing you to cast them. For example, if the top card of your library is a green creature card and you control Garruk's Horde, you can cast that card as though it had flash.

You still pay the costs for green creature spells you cast.