A birds egg in my garden today - HELP!

My dog brought me a present this lunch time - found somewhere in my garden. Unfortunately it is a bit chewed.

Please can anyone identify it for me, and is it likely to be this years, or could it be an old one?

It is white with no marks or speckles. The membrane under the shell is a sort of grey colour. The shell is clean.

 

 

Cheers, Linda.

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