As I mentioned for day two, God has rolled up His sleeves. He wasn’t finished with the project for days two and three, and will complete it today.
Today, He creates the first living thing: vegetation. But, before He can do that, recall that there isn’t any dirt yet in which they could live. We have the heavens, plus water above and below those heavens. The earth is no longer “formless and void”, as it was at the beginning. But, neither water nor air by themselves are good enough for normal plant growth.
So, god causes all the waters under the heavens to be gathered up into one place. Alongside that, or possibly surrounding it, there is dry land. Or, rather, dry land appears separately from the waters. Since the big ball of water He is working on (inside the heavens) is becoming what we know as planet Earth, He must also have created dirt inside the ball as well.
So, this sheds light on the somewhat cryptic “Let the waters below the heavens be gathered into one place, …” (Genesis 1:9) God made all the land, and causes the waters to be gathered into an ocean or several oceans.
NOW God calls His creation “good” again. His two-day project of creating the bulk of the earth is complete. But, He has more to do on day three: He creates vegetation.
Then God repeats Himself, and says the earth brought forth the vegetation. So, the rocks and dirt just sprung vegetation out of themselves. This kind of sheds new light on Jesus statement “I tell you, if these [people] become silent, the stones will cry out!” A serpent (Genesis 3:1) and donkey (Numbers 22:28) spoke. God can do pretty much anything He wants to, so making rocks talk would be no big deal. (I wish I knew what they would say, but I suspect if they DID have to speak out, it would be in judgment, and that would be the end of the road for humanity. So, it may be best we do not know.)
Then, God calls His creation good again on this third day.
It was a solidly productive day.
 Technically, in Biblical terms, plants aren’t living. “Living”, as defined in Scripture, means having the breath of life. But, to our modern ears, plants are living, so I chose to use the modern usage of the term.