Lemna minor (Duckweed)
Salvinia minima (Water Fern/Water Spangles)
Free! Pick up in Portland (ME).
The floating plants in my tank have grown to the point that I need to cull some and I'd rather give them away than compost them. I have bladder snails so there may be hitchhikers. Neither of these are listed as invasives, but as always be a good steward and make sure the plants stay in your tank and out of our natural waterways.
If anybody wants to trade, I'm looking for Malaysian Trumpet Snails .
Edit: Still composting handfuls on a regular basis!
I'd rather not deal with shipping. But if you don't mind having something shipped it can come from anywhere in the country, check the SnS forum. Lots of people provide free stuff, you just pay shipping. Probably should wait until late spring to keep stuff from freezing though.