What is it?

[boojababy]

Found these pieces when digging a garden in my back yard.

 

[boojababy]

Found these pieces when digging a garden in my back yard.

Backside

 

[DaveNV]

Looks like pieces of milk glass. 1930s or ‘40s.

 

[JimmyCT]

Or possibly a porcelain liner

 

[thepest]

(JimmyCT beat me to it) looks like the inside glass seal from a zinc canning jar lid

 

[boojababy]

It does look like from a canning jar lid cool.

 

[PDH]

I'm on the canning jar lid team