Pockets in the 18th century and the 1840s-60s were worn over the petticoats and under the skirt. The skirt had openings in the side seam to access the pockets.
‘Pockets are either worn tied round the waist, fastened into the petticoat, or buttoned upon the stays. When fastened into the petticoat, they are made of the same material, otherwise of dimity, calico, jean, twilled muslin, and sometimes of nankeen or brown jean.
I used white cotton fabric for my Victorian pockets. Here’s an 1857 painting of pockets and a painting of 18th century pockets. And three antique white cotton pockets: late 18th to early 19th century, 1785-1810 and Victorian pockets.