Warm pocket shelter
We all have seen the emergency blankets that are for sale at the local store. Well I can tell you from experience they don't work to keep you warm but are very good fire starters. However, if you carry two (2) of these mylar wonders (space blankets) you can make a very warm viable shelter.
First off, take one of the space blankets, open it up and lay it on the ground. Now pile dry leaves and grasses on the space blanket. Make it as thick as you like, the more material the better. Now open the second space blanket and lay it on top of the dried material, like making a sandwich where the space blankets are the bread and the dry material is the meat of the sandwich.
Lay down on the space blanket sandwich .. Grab the edge of it and roll your body into the sandwich making yourself a burrito ... Instant shelter because the space blankets are waterproof and the leaves provide insulation.
I've used this method and you don't need much time until you’re toasty.