First, make a template for your hat. A basic half-oval shape is perfect. I just free-handed mine. For a 0-3 month old you will need to make your template 7 1/2 inches wide at the bottom and about 5 3/4 inches tall. (Most 0-3 month old babies head circumference measure around 14-15 inches in diameter so if your little babe has a bigger noggin you may want to add some more inches to the width.)
Next, take your felt piece and cut one 4 x 4 inch piece and one 1 inch by 1.5 inch piece.
Next, fold the larger felt piece in half and cut out a few triangles so that you have a very oblong star-shape, like the picture above. It doesn’t really have to be symmetrical since blueberry leaves are all types of crazy shapes.
Now, take your two hat pieces and place right sides together with the stem piece centered at the very top portion. Sew the two pieces together using a zig-zag stitch to give the hat some extra stretch room.
Flip your hat right-side out and make sure it’s not too puckered at the seam. You may need to snip your seam allowance at the curves a bit.
Finally, take your star-shaped felt piece and pull the stem through the slit. Hand-stitch the leaves to that hat taking care not to sew the front and the back of the hat together.