Using the burlap, trace the size circle you would like with the bottom of a small bottle and cut it out. To keep the edges from fraying add glue all around the edges and allow to dry. You can use all felt if you like for your pieces but I like the texture that using burlap adds for the head. 

Once the glue is dry add a nose and mouth to your face with a black sharpie or paint pen, try different expressions.

Keep one piece of felt whole to use as the background, whatever color you like, fold it in half and slip it in the top of the bag.

Cut pieces of felt and flannel into very basic shapes of shirts, pants, and overalls, your kiddo isn’t looking for perfection so don’t sweat it too much. Add a moon/sun, bats, trees, hay bales, maybe even little bits of straw from yellow felt. All three of the different fabrics will stick lightly to each other making a great travel flannel board or paper bag scarecrow craft (even though it's not in a paper bag).

Add buttons and googly eyes to your bag.

Finally, I like to “sneak” in an educational aspect, even if your child is not quite ready for spelling words adding letters to spell out scarecrow, fall, pumpkin, etc… will at least help them become familiar with letters and how the combine to create a word. Have them identify each letter of the word, make the sound of the letter, or match the letter with the beginning sound of each object on the flannel board.

Once that's all in there, seal the bag closed and put it somewhere you'll remember to grab it on the way out to the next adventure where the little one might need an activity to keep curious hands busy.