Fields, small woods, hedgerows, that kind of area?, but no pond materials like reedmace, how about fireweed, greater Rosebay willowherb? We call it fire crackle when we use the dried hollow, fibery stems; border mallow and the like works the same way and dried out winter stalks from thistles and mugwort (use the dead leaves as well, but carefully, it's an old cleansing herb, a hearth herb) work too. I used the papery thin tubes of old bluebell stems last week. I find the leaves from grain stalks, like oats, wheat and barley very good; the fine peelings from birch, or dried willow bark too. Even the fallen leaves from holly work.
'Nests' can be made quite effectively, from gathered and wrapped into a kind of wreath shape, from the thin twiggy tops that come from the birches, but I do like the fungi best; either Fomes f. or Betulina piptoporus for my area. I don't know what you find in yours, there seems to be a lot of cramp ball mentioned on the forum as available south of the border.
Enjoy the course

, and will you do a write up so the rest of us get an idea of what was covered?
Cheers,
Toddy