Seems to me you have a problem - you’re trying to avoid mechanical terms like “design”, but if you also reject the kind of concepts in A-T or Platonist thinking, it’s not clear that you have any possible model _other _ than a mechanical one, only somehow one in which inanimate nature offers creative suggestions (undesigned?) and God reacts to them - which, as Ashwin rightly says, is pretty much Open Theism, the God whose creation forms him as much as, or more than, vice versa.
You talk about the sculptor working in cooperation with the stone - but in the case of the world, God the Sculptor is the only agent available to make the stone, so he is working with what he himself has already made.
And although Eddie was willing to run with it, the idea that “Let the earth bring forth vegetation” implies the co-creatorial power of the earth ignores the rather more obvious phenomenological reading - that the earth brought forth plants, as it does to this day, because somebody put living seeds in it (as described of God in Ps 104:14-17). Job 28:5 also describes food coming from the earth in the present - and there is no idea in this of co-creation or evolution - just the blindingly obvious fact that plants grow from the earth, and that God makes it so by his sovereign power.
I dare say that when God said in the previous section of Genesis “Let the waters below the heavens be gathered together” he was not talking about the creative power of water, but the creative word of his power. Actually, most likely the omission of “making” verbs on some of the days, all of which begin with "Let there be… " statements, has to do with literary considerations - there are exactly seven uses of “bara” in the creation account.
In fact, in this account, which is all about “What God did”, remember, and not “the various forces that shaped the world”, God’s work is set forth as describing, calling, distinguishing, approving, blessing, commanding, creating and making (or more generically, “doing”, encompassing all the other activities.
If the earth did have power to bring forth vegetation on its own, by the way, it would be an Aristotelian power or potentia (built into its nature by the wisdom of God, as Eddie rightly says) - there are no such powers in the mechanical philosophy, but only laws imposed by God himself on inert matter.
So what are we trying to preserve here, in protecting God from the acccusation of planning ahead, as Scripture repeatedly speaks of him doing? Is it something like “spontaneity” in nature - and if so what does that even mean? I sense some incoherence here.