Here's an instructable on how to do this type of embroidery onto a pillow. I did it more freeformed, randomly placing the mirrors around but you can do it however you want.
Step 1: Supplies
1. Whatever fabric you want to use. Keep in mind, you're going to be doing a lot of dense stitches and the mirrors weight a bit so make sure there's a tight enough weave and the fabric doesn't give too much.
2. Embroidery thread. For this, I used silk thread that I bought in India. The brand is Namaskar and might be able to be found online somewhere.
3. Embroidery loop. I couldn't find my wooden one, but use wood over plastic. Make sure it's not too huge a loop.
4. Round mirrors. Again, I bought these in India but Michaels or any craft store should carry these. I used 3 different sizes for a bit of pattern variation but you could do it all the same size ones.
5. Embroidery needle. If you don't want to get an embroidery needle, you need to buy a needle with a big enough eye to fit multiple strands in.
7. Threader (optional)
If you want to make the pillow, you will need:
1. Pillow stuffing.
2. Sewing machine. You can always hand sew but this is faster.
3. Pinking shears.
5. Chalk line tool. I'm sure there's an official name for this. It's the tool that creates a line of chalk when you run it along a surface. Ask at a craft store if you're unsure.
Step 2: Thread the Needle
1. Measure out about 24 inches of thread.
2. Repeat 6 times.
3. Group together so that all 6 are aligned together.
4. Thread using a threader or by eye if you can.
5. Drop the needle into center of the thread.
6. Make sure the thread is taught when pulled against the thread and knot the end.
7. Cut any excess thread off the end of the knot.
Note, that if you are using a small mirror use about 6 threads, which when folded around the needle is 12. With larger mirrors use 8 or 10.
Step 3: Square Stitch/First Step
1. Place the mirror onto the top side of the fabric.
2. Poke the needle up from the bottom of the fabric so that is touching the mirror anywhere on the edge.
3. Keeping the mirror in place, poke the needle through directly across from where you pulled it up.
4. Do the same, up and across perpendicular to the first stitch that you did.
5. Repeat this so that you eventually have two parallel lines. It doesn't matter the order that you do them in, just that you alternate directions.
Keep in mind:
--Keep the thread taught and tight against the mirror!!
--Where you poke through the fabric should be as close to the mirror as you can get it. This will make sure that the mirror doesn't shift.
Step 4: Double Stitch/Repeated Step 2
1. Poke the needle up from underneath the fabric. Hold the thread with your left thumb and poke the needle underneath the threads on the mirror.
2. Pull through the thread so that it goes through the loop created by your thumb and the hanging thread.
3. Pull taught. This will force the thread that's on the mirror to give...that's good. These stitches will eventually pull the tiny square that's created by the parallel lines of thread on the mirror to turn into a circle.
4. Hold the thread with your left thumb again.
5. Do a tiny down and up with the needle, alongside the edge of the mirror.
6. Pull the thread so that again, it goes through the loop created by your thumb and the hanging thread.
7. Pull taught.
Step 5: Repeat/Troubleshooting
One of the biggest headaches that will happen in this process is ONE thread will not pull taught and loop up. If you notice it when you're doing that stitch, pull every thread until the loose one pulls tight. It gets annoying but it's the only way to solve it.
You can also control the shape of the circle that forms in the center by controlling how taught you pull the thread when you're doing the first of the two stitches. If you do a practice mirror first, you'll see how to control it.
When you're going around and doing that first of two stitches and reach an area where two of the parallel lines intersect, go through both of them. These stitches strengthen the hold.
Here are some detail shots along the way.
Step 6: Finishing Embroidery
2. Find a stitch and poke the needle between the stitch and the fabric WITHOUT poking back through the fabric. This will create a knot
3. Repeat a few times until you are sure the mirror and stitches are secure.
4. Cut off excess thread.
You're done...unless you want to make a pillow...
Step 7: Make Pillow
1. Iron the fabric from the backside.
2. Line up your front and back fabric with the backsides facing out so that the sides you want to have on the outside are touching on the inside.
3. Chalk out straight lines to follow.
4. Pin the fabric to keep it in place.
5. Sew the two pieces together around ALMOST all four sides, leaving about 2 inches unsewn.
6. Cut off the excess fabric around the edges with pinking shears.
7. Flip the fabric inside out.
8. Stuff with pillow stuffing.
9. Handsew the last two inches.
10. You're DONE NOW!!!!!!!!!!!!