Frost on stinging nettles. These plants will die back once it gets a bit colder.
I did go a few days without building the daily fire during the Thanksgiving week, but yesterday I was back at it. Which means that I will clean out the stove this morning to prep for today's fire. We're also getting a fuel-oil delivery today which should take us through the winter. We use the central heating in the mornings to warm up the house, then the fire in the afternoon to keep it comfortable.