Don't do anything with them until you find out for sure.
If they are worth something on the 'antique' or 'vintage' market, you will ruin the value by sewing them together. A possible collector will not want them if they're altered in any way. A collector might possibly have them professionally cleaned or treated by a textiles conservator.
Why don't you GOOGLE "antique textiles"?
Another idea: offer them on Ebay with a "hidden minimum price". A bidder makes an offer...and if their offer isn't making the 'minimum' bid amount, they are told to bid more. If they never sell at the minimum, you keep them. However, Ebay may charge you a nominal fee for the service they provided to you for the 'no sale' auction.