My mum always taught me to keep a button jar, because she told me 

"You never know when you will need them"

...and how very true that is.

They are a cheap and cheerful enough Embellishment for you to add them in quantities for a stunning effect.

This card was created with just small pearlised buttons for a lovely look

They have been added to a heart shape, and then layered onto the scalloped edge  heart shape with foam pads between the layers 

Another simple and effective idea is to add the buttons as the edging to any of your shaped cards.

Choose small ones that all match, and just add a few of them randomly along the rim

Try using permanent  marker pens to alter the colour of them to suit your project.

Especially good on wooden ones.

Or simply use matching buttons and add them as decoration to your shape.

These have been added under some acetate to create the decoration for a Christmas Card

But whatever you do .. 
Don't throw them away.

They are cheap ... and far too valuable to just waste.

If you want them to match your colour scheme, and you have lots of scraps left over from that project then take a look  at this
handy little gadget. 

You will be able to add these to your button cards in matching patterns and colours to suit.