The bullet is a civil war yankee .58-caliber Williams "Bore cleaner" Type One bullet. However, having the Jenny Wade House scene inside it makes it worth considerably more than its mere bullet value to civil war relic collectors. Sometime after the war ended, various types of original (not reproduction) bullets were micro-altered to show a Gettysburg Battlefield civil war scene inside them. I've never sold or owned one, so I cannot tell you its current value... but I know it's worth good bit more than the large-cent your brother traded for it, unless that coin was a rare type or rare date.
I should mention, in civil war relic collecting, there is a subset called Gettysburg Collectibles, and prices in that area are sometimes crazy high in comparison to the price for the same relic without a Gettysburg connection. That is why so many civil war relics on Ebay are claimed to be from Gettysburg. I've been telling people for 30-something years, if all the relics that were supposedly found at Gettysburg were brought back to the town and stacked in a pile, you'd be unable to see the town.
To prevent misunderstanding, let me state clearly, I am NOT saying your brother's Jenny Wade House scene bullet is a fake. I've never heard of anybody faking such bullets, because it would be too difficult to do convincingly.
