Hand Carved Wooden Plate

Wondering if any one can give me any information please !

I was wondering if there was any way to indentify how old the wood is on a cut like this?

Also does any one know what causes the dark spot on the side of the wood plate?

What type of wood would this be?

I would love any info or input.

I bought this plate at a church yard sale. The seller said it was in the basement for a long time and as soon as I saw the detail and craftmanship I bought it off of him.

The fabric and nail are original and the nail seems to be hand forged.

No marks or signatures.

I found a painting that dates around 1880's that seems to match it.

 Thanks for any input in advance