I freeze these in plastic cups. Each cup has about 85g-100g of elderberries. I am lucky enough to have a freezer for my non food stuff but if you don't have this just make sure that any berries are clearly labelled and well wrapped to prevent any contamination.
I don't freeze everything I collect. These rosehips have been dried in the oven. When I do collect berries I make sure that I only take about half from the tree or bush so as to leave enough for the birds.
I use fir cones as well but these stay in a dry box in the garage.
I am being very disciplined at the moment and resisting the urge to dye up some fibres. I really need to finally complete my C&G diploma and have made huge progress since FoQ as I am now over 50% finished. Trouble is life is starting to get in the way again, planning for workshops, making samples etc and I have a date with a Year Four class tomorrow. Oh well I will keep on stitching, keep on stitching and collecting goodies to dye with!!