Found a whole pile of things at Long Meg when there on NYD. Along with the usual holly, twigs, coins etc were several tealights (incl. three glass jars to hold some of them) and an impressive array of fruit - including the well-known native varieties of orange and pomegranate!
I didn't have a bag with me either... but luckily the prettiest tealight holder fitted just nicely inside my pocket. Sadly, no pebbles had been left.
During another recent visit was to a large local cemetery, it'll never fail to amaze me how people can think that plastic bags and cellophane wrapping can be a suitable tribute (was all that was left on some graves)