Some years ago I found a very large woman's OLD dress
in an estate sale. It looked like it had been worn and washed
for a hundred years. It had small pinkish brown roses on a cream background.
For my sister's Civil War Reenactment clothes I used my Grandmother's old sun bonnet as a pattern and made her one. I had enough fabric left over to make her a waist apron
with small ties.
She said it looked so authentic that she could have sold it several times over!
Look in all the odd spots such as estate sales and antique shops. Just might find what you want.