These are the rushes used to make rushlights.
Pick a few, soak them an hour or two if you have time (they peel more easily soaked).
The white pith inside will be the wick. Strip away the green, but leave one or two strands to strength your taper.
Leave them to dry for a while. Then they need dipping in some sort of fat. Poor people used tallow, which is animal fat, left over from cooking.
I will use beeswax, which will smell much nicer.
Here they are, a pot of beeswax rushlights...
They give a good light, bright enough for reading or writing. This room was completely dark.