Let's talk about the simplicity of eco printing on paper.
Here are the supplies (what I used)
Take a walk and scout out leaves, branches and flowers. The flowers should have some strong color. This is akin to flower pounding, the more intense the color, the more potential. However! Some things will surprise you.
Paper: I'm using my standard Stonehenge, which is a smooth heavy printmaking paper. I tried some watercolor paper (cold press, rough) which didn't work as well.
A big pot with a lid. I have a canning pot from the thrifts which includes that insert thingie. You could use a steamer.
A flat base that fits into the steamer. I happened to have a rusty bottom of a springform pan. It works.
Something heavy to weight down the paper. I have a rusty cake tin that I filled with stones. A brick or two would do the trick.
I wet my paper in a container full of warm water for about an hour. Today's batch was wetted down in water + alum. We'll see what happens.
Now just start inserting your plant materials between the papers. Squish it down really hard. You want as much contact as you can get between all the materials and the papers. Weigh it down with your heavy thing and squish the daylights out of it. Steam it for 2-3 hours. Then let it sit until it is cool enough to handle. The extra time in the pot is a good thing anyway.
I have to leave the house at this point or get busy, very busy elsewhere. I can't resist peeking :)
Immediately after I posted one of these Windfall Papers to FB, Artist Laura Ryan contacted me about her recent article in Pages Summer 2013, one of Cloth Paper Scissors quarterlies. Ain't social media awesome. I ran out and got the magazine and saw her method which is a bit different from mine so you might want to get your hands on it and experiment some more. Laura lives in CA so has access to eucalyptus.
Most of what I know about eco printing comes from India Flint's amazing book Eco Colour which addresses eco printing on fabric. The past couple of years worth of eco dyeing has been helpful too.
A word about eucalyptus. India uses it extensively. It is native in Australia. The only place you can get windfall Euc is in CA (where it is agressively invasive). You could buy, of course. But be aware that it is extremely popular in eco dyeing circles. There are plenty of other plants that you can use, though.
I hope you'll try this!