My sister works in a day school in Southern Texas. She gave her kids aloe plants for Earth Day. I thought it a nice gesture, after all, it was the Lord who created the heavens and the earth and all the wonderful plants we see on earth.
I found a good article that puts Earth Day into perspective:
http://www.answersingenesis.org/articles/2010/04/22/earth-day-creationist-perspective
And this link to a new DVD that sounds fascinating:
http://www.themysteriousislands.com/
On the day some have named Earth Day, I planted spinach, radishes and lettuce in my garden. But I would have planted them regardless of the day having a name. It was a beautiful day!