Since God is said to provide light in the eternal kingdom in Revelation, and he created light (...let there be light...) before he created the Sun and stars, I would think he himself provided the light for the plants. Also, how many plants die without 1 day of light, as the Sun and stars were created the next day? I think we forget to ask how reletivity plays into a 6 day creation. 6 days for whom? Maybe it depends on your perspective. All I really know is that I don't know much but I've never had a reason to doubt God.
I can accept your analysis of the "six day creation" and not doubt your faith.
However the thing that irks me are the literalists who demand everyone accept their explanations, as if THEY were the ones who created this universe.
Usually I dont even get worked up over the issue, and I'm not even sure why I did in this thread.
Anyway, carry on.