I'd guess it's a vine, wild yam, (Dioscorea villosa) I spot it occassionally near streams here in Michigan. It is never very abundant. The seed pods really stand out in the winter, though.

If not wild yam, take a look at bladdernut. Bladdernut is a shrub/small tree usually found in river floodplains around here.(Staphylea trifolia). It has a 3 part papery fruit with a few seeds inside that rattle around when the wind blows in the winter. Was the seed pod you saw flat or more like a 3-part papery oblong pointy ball? (Wow, that doesn't sound very clear !?!) I think I saw bladdernut shrubs for sale in a catalog with some more appealing name but it escapes me right now.

Another small tree with papery seed pods is wafer ash, also known as stinking ash and hop tree (Ptelea trifoliata). The wafers are single but are clustered together, sometimes in threes.

I'm curious to know if it was one of these you saw. I know several streams near here that have 2 or 3 of these species growing along them. I'd be watching for wild cucumber and virgin's bower in the same areas.

Here is a link that might be useful:

Naturegirl is right! The pictures of "wild yam" seed pods are exactly what I found. Thanks for solving the mystery! Now the trick will be to get the darn things to grow
Thanks again naturegirl!

George

Good to hear you know the ID now. I only learned of this plant somewhat recently. It is easiest to spot in the winter...don't remember ever seeing the summer flowers and I kayak through suitable habitat alot! Maybe I'll try to get some seeds and grow it, too. It would be a good reason to go out hiking through some of my favorite creekside areas. Even if I can't find seeds it would be a fun afternoon.

Good luck with your seed starting.