Gents,
When I first started using a percussion shotgun, an old gunsmith told me to use ivy leaves as wadding for when we were shooting wood-pigeons or ducks over laid corn (barley...this was the UK) at harvest time, so as to not set fire to the crop.
At that time, we still used to load with paper as wadding at times, so the ivy leaves seemed a good idea to try.
He said just roll a couple up in a ball and ram them down, then shot and another leaf or bit of grass to keep the shot in place.
It works like a charm, still very nice even patterns and no chance of anything smouldering and setting fire to the straw in dry times.
Don't leave loaded overnight. The leaves turn damp and so does your powder.
Over here, I found any tough leaf will do. Black poplar even.
For some reason, I don't expect many replies!...but it does work. :-)
Richard.