1860s fabric and ideas help, please!

[sohewasall]

So, for my 1860s fancy day dress, I *think* I'm going to go with a white dress with colorful trim. Notice I said think, because seriously, I'm not so sure. I love love love white dresses, as you all know, and I think a white day dress won't look too wedding-like. One issue I'm having is trying to determine the fabrics used on these dresses. Cotton muslin? Silk organza?









I can never decide...