The sketch that I worked with for these cards is the following:

Since I didn't have any buttons in the colours that I wanted, I decided to make my own! It's fun, easy, and means you will always have co-ordinating embellishments!
I learned this technique from Rebel Inker (she has a video tutorial if you are visual).
You need the following materials:
A circle punch (I used 1" for the bigger ones and 3/4" for the smaller ones. I have also used 1/2" for mini ones)
Cardstock and designer paper if you want to make a fancier button
Crystal effects
Crop-a-dile/hole punch
Sanding blocks
Step 1: cut several circles out of your cardstock (I did 4)
Step 2: glue them together (I used the Tombow white glue)
Step 3: punch out your top circle out of cardstock or dsp and glue to your stack of 4 circles
Step 4: sand down the sides so that the layers blend together
Step 5: punch out two holes to make it look like a button
Step 6: add crystal effects to add 'shine'
Step 7: Let dry (be careful not to touch them) and then use on your project!
for a little extra <pop> add a second layer of crystal effects once the first layer is dry.
My first card I couldn't seem to add buttons to the top right corner to make it turn out nicely - I still like the card so I thought I would share it with you anyways. I had more success with my second card (and the awesome Sweet Pea DSP!)

I hope you like my square cards! I might try to make a circle one later this week :)
Happy stamping!
Mitra