This is my first post on what looks like the perfect forum!
Not a perfect forum. Interesting certainly. But the lack of UK participation makes it pretty much moot. You be better off at www.thegreenlivingforum.net for UK based advice.
Nicole's suggestions definitely apply to the US. A couple of those are considered invasive here in the UK and wouldn't be allowed. Burra's suggestion however are spot on the mark. Daffs and Crocuses are definites that would work well. Wild Garlic as they like gloomy moist environments.
RHS has some very good suggestions which should work well in your clearing.
https://www.rhs.org.uk/advice/profile?pid=100
