Ask Poison Control at 1-800-222-1222.
They can search their extensive database for reliable info.

The WebMD site says this plant is unsafe in any quantity.

Here is a link that might be useful: About Lesser Celandine

Shucks. There goes that idea.

You may want to check out eattheweeds.com, if you haven't already.

That's a new one. Thanks!

I wouldn't even think of eating anything in the Ranunculaceae.

"Ranunculaceae contain protoanemonin, which is toxic to humans and animals. Other poisonous or toxic compounds, alkaloids and glycosides, are also very common." (WIki)

Here's a super random question: might the tubers be poisonous to ducks ? I'm not sure if I just discovered a brilliant way to get rid of lesser celandine, OR accidentally kill mallard ducks, OR if it doesn't kill them, might I be inadvertently causing the LC to spread via the ducks digestive track not "composting" them properly...

I just put a big pile of LCelandine into a hole I dug in the center of my compost heap and before I got around to covering it up to let the heat digest them into oblivion, there were 2 Mallard Ducks pecking away at the pile. I don't know if it was a coincidence that there was something else mixed in with the tubers & greens that they were noshing on or if it was the tubers themselves. I know it's a shot in the dark, but any thoughts? Should I cover the heap? Or let them continue to go at it?