Here's a super simple sachet to make:
You'll need some muslin (or other lightweight material), pinking shears, sewing machine with contrasting thread, a rubber stamp and ink pad (I used Distress Inks) and lavender.
I just cut pairs of muslin into roughly 2 1/2" x 3 1/2" pieces. I didn't measure, just cut the pieces two at a time so that they match. Using the pinking shears provides a decorative edge, keeps the sachets from fraying and - bonus - you don't need to turn them inside out.
Use your stamp to decorate the front of your sachet.
Spoon in a couple of teaspoons of lavender. Then just sew up the last seam. Done. I made a pile of these and put them in my fabric storage drawers.
A quick and handy gift. I'm going to make larger ones to throw into the dryer with the laundry.