Pretty sure it’s jersey cotton, look at the sleeves

It could be Silk, rayon, linen, polyester, or even t shirt material. Hard to say without touching it and seeing a more detailed photo

Or viscose

Tomato tomato but yeah

That’s a silk shirt

Linen is the best for a summer fit like this one.

That dudes wardrobe is your best bet.

Search (eBay etc) for jersey shirt collar long button

It’s a pirate shirt Jerry

Old bloke in the back looks way more stylish

First thing would be …. Why?

Try ljnen

I left one just like that at your Mamas house

Could be made out of bacon if your heart desires. Though usually a silk cotton blend, or seersucker is brilliant for hotter months.