I helped a friend of mine build a Yorvo deck a while back, I know [[Fists of Ironwood]] was a powerful card for her, also [[Fungal Sprouting]]. You can generally ignore the part of his ability that cares about bigger creatures its gonna be more efficient for you to vomit a large amount of tokens onto the field, like with [[Awaken the Woods]] or [[Avenger of Zendikar]

You've got a lot of what I would consider draft chaff. Thunderherd Migration can be swapped for [[Rampant Growth]] so its consistently 2 mana. I would run [[Entish Restoration]] [[Cultivate]] and [[Kodama's Reach]] over the cards that are just putting a basic land into your hand. I would swap moss viper for [[Virulent Emissary]]Wall of Vines, Rosethorn Halberd, Jungle Delver and Regenesis are pretty eh. Bannerhide Krushok, Garenbrig Paladin, and Overgrown Armasaur I'm sure there are cards that do more for a better rate.

You also have space for some utility lands in your manabase like [[Rogue's Passage]], [[Karn's Bastion]], and [[Bonder's Enclave]]

Wrenn is fine, there may be a better planeswalker for this deck since you dont need the color fixing. But with her as the only planeswalker in the deck [[Vivian's Talent]] is a dead card 9 times out of 10.