Mrs. Bennet's Lace Cap: Who could forget Mrs. Bennet's lace cap? It just suits her so well! It seems to be made out of some kind of sheer material. Something that appears to be a little pink flower sits right in the middle of the edge of the cap.
Charlotte's Lace Cap: Charlotte would wear a lace cap before she was married only when going outside in her bonnet (more on that later). But, since she married Mr. Collins, she always wears the lace cap except for some evenings at Rosings. It's a fairly plain lace cap: no ribbons or flowers. There is a little bit of lace with a design, but overall, it's a very plain cap.
Caps under Bonnets: Of course, some women wore lace caps under their bonnets. You can see here that Mrs. Gardiner and Charlotte both wear lace caps under their bonnets. This picture of Charlotte was from when before she was married; perhaps because she was twenty seven, she thought that she wasn't going to get married?
I used this source to find out information about lace caps: here. If you want to read further, you can try there.