Dating family buttons- deco?

[Arabella's Treasures]

I have just acquired my grandmother and great aunts button basket and am finding some great little jems. However I am a little stuck on dating these 3 I have found.

The front is a thin plastic type material and the back is a thin metal/tin?
Can anyone help me on dating them?

 

[Circa Vintage Clothing]

Lovely buttons: how big are they? They look '20s to me, although I wouldn't quite call them Deco. I've only seen this sort in large varieties, hence my question.

 

[Arabella's Treasures]

Sorry, forgot to put measurements, 3cm diameter. We think they might have come from my great great grandfather's drapery shop.