my seed swap site is
http://www.seedswappers.co.uk mostly veg and garden flowers - but do have wild flower mixes listed on there i think - i save seeds every year anyway - happy to collect if i can help someone out
it's not ransoms we have - is jack by the hedge (garlic mustard) - which i call garlic hedge
- i will gladly collect seeds from that later in the year if you'd like some.
you have struck nail on head though - by stating the obvious - light is always going to be an issue - especially with a dense canopy - most of our flowering species are around the boundaries and in recently (last 5 years) coppiced areas - not much grows under the mature stuff
wood anemone would grow under dense cover - but we don't have any on our site i'm afraid - although i do know know of a lovely patch just a few miles down the road
another thing that might grow on the borders is woundwort - bees love that too - although it can spread quite quickly the roots are shallow so are easily controlled (i grow it in my garden, but then i am an eco-gardener - so the bees come before me
)
i've got to sort through my self collected seed boxes within next week or too - so i'll have a look to see what might be ok in the wood - and post back in this thread - but i am going to be too busy, certainly over coming week - as my dad is really poorly and i'm on "woods duty" until he gets better