Well, I've got to put in my 2 cents on this one. When I go on a trip,
I bring an extra cloth bag. The finds are wrapped in napkins, paper
towels, TP etc. and put in baggies, with a label as to where these
were found..  Then, as I collect
from different areas, these go into the fine containers I've
been saving and rinsing from my fast food meals.  Usually one
container is fine for the finds from a particular day or area.
By the time the trip is over, I have containers all filled and
ready to go into the cloth bag for the homeward trip.

Karen

PS - If you need more protective containers, one can get cheap
plastic food containers at the 7-11 type places, everywhere.