Mix the lavender, orris root, and essential oil in a bowl and set aside.
30 grams dried lavender, 10 grams powdered orris, 3 drops lavender essential oil
Cut two 9x6 inch pieces of fabric. If using a patterned material, make sure you're sewing it so that when you flip it inside-out, the pattern will be on the outside.
Fold lengthwise with the long sides together, and sew along the long side and one short side. A running stitch is fine here because the bag won't have much seam-stress, but you can do a back stitch if preferred.
Fold the (unsewn) top of the bag down one-third and press it flat with an iron. This will prevent the raw edge from showing once the bag is turned inside-out.
Carefully turn the sachet inside-out, pressing gently into the corners if needed.
Fill the first sachet with half of the lavender mixture and tie off the top with a narrow piece of ribbon in a bow.
Repeat the same steps for the second sachet, and then make as many as you'd like.