I have about 220-220 Allen and Ginter flags of different countries. My grandmother sewed them together into about 44" x 44" tablecloth looking thing. Is it valuable, or only to me??220 Allen and Ginter cards sewn into a giant blanket? I would love to see that! Unfortunately, sewing cards together kind of implies "poking several holes into each card" so the value of the cards goes way, way down at that point. There are fools like me who will buy cards in almost any condition, but the majority of serious non-sports collectors don't look kindly upon holey cards. Whatever you do, don't take that thing apart! If you separated them and tried to sell the cards individually, you might get a few bucks for them on eBay but it's a much better item sewn together just for the oddity and the sentimental value. Cards in poor condition are plentiful, but an Allen & Ginter tablecloth thingy is pretty unique and hard to find.
There are four cards from the set that are really scarce however and are valuable if you really needed the money for an operation or something. The four that are hard to find can be found here at the very top of the gallery. Roumania is the absolute toughest, followed by Corea. These cards were apparently only released in a couple of printings. The two others are variation cards. The Great Britain Royal Standard tough variety has a bright yellow sun instead of a gold sun and the Belgium fancy card has a package of cigarettes in the background. I'm not sure of the exact value of the cards though so don't expect to get rich even if your grandmother did sew a couple of them in there. Even if you do find a scarce one I think you'd be much better off keeping the set in one piece.