Start by finely chopping up the balsam fir needles and small twigs.
Spread them in a thin layer to dry in for a day or two. OR - spread them on dehydrator trays, and dry at about 100°, for 12-15 hours until fully dry.
Make the pillows
Print the 4" template linked above (or another size if you prefer a larger or small pillow.)
Using the template, cut two fabric squares for each pillow.
With right sides together, sew around the pillow, leaving 2.5" open along the middle of one side.
Flip pillow right side out.
Fill and finish the pillow
Fill the pillow with the dried, shredded balsam. A small funnel can help with getting the balsam into the pillow. Leave just enough room to stitch the final seam shut.
Using needle and thread, securely stitch the opening of the pillow.
Notes
Care: Spot clean as necessary. To wash, filling must be removed. Wash and dry fabric separately, then re-stuff and stitch.