One thing I carry that has been extremely useful over the years and weighs virtually nothing is a sheet of Tyvek (or equivalent house covering material) folded over on itself and tucked in my bag.
It is useful as a makeshift rain cover or more typically for me, as I am usually near a pond or water source when I shoot dragonflies, something dry and waterproof to sit down on temporarily or set my bag on. It has the added benefit of being mostly white so you can see if anything is crawling (or slithering) up next to you. When you’re done you can just pick it up and shake it off like a picnic blanket.
It is a synthetic material from a company that may not be popular in the naturalist community but I have used the same piece (given to me by a friend who had excess on a backpacking trip) for over a decade and been able to get shots or shoot in environments I wouldn’t have without it.