My peonies needed support, and I had an old chair with no seat. Situated over a peony bush, it let the flowers grow through and supported them.
It reinforces the focal point of that flower bed, too.
Reuse newspaper and grass clippings to mulch around flowers and create walkways.
Put down 2-3 sections of newspaper, thoroughly wet to hold it down while you spread 4-5" of grass on it. After a year the newspaper has pretty much decomposed and the worms love it!
Buy locally grown produce, or grow your own. Either option reduces the energy some commercial farm uses to grow its vegetables and fruit, and the trucks use to take them to the grocery store. Besides, we all know how much better locally grown tomatoes and peaches taste. (I am so blessed to live near the orchards in Cana, Virginia!)
I save all of my vegetable peelings and dead flowers for the compost. Household containers like this one have charcoal filters which eliminate smell in the house. Then they get dumped into my large composter outside.
If you don't want to build a compost bin, you can use the method my French friend taught me. She had 3 shallow pits in her yard. Every year she used one for her compostables, adding a thin layer of dirt and dry grass or leaves every once in a while. The second year she used the next pit, leaving the other two to slowly compost on their own. By the time you get to the first pit at year four, the microbes and worms have produced nice soil. Empty it and refill the pit with that year's green scraps.
Happy Earth Day. What do you do that I could add to my list?