This helps movement be a bit easier since you cant side step. Here is a tip as well, you can rotate left or right way quicker by tapping the aim button quickly while turning in place. The controls are bad but you get used to it quickly. These items can be worth less than normal if you let them fall into the water. It doesn't control like other 3rd person games and the aiming is strange. These treasures are found numerously throughout the game and don't join with other items. You are safe to sell them as you find them because they don't appreciate in value (besides the dirty items that can only depreciate in value). These are the treasures that you find that don't combine together. The number next to the top item in the list is the amount you'll get if you are patient enough to combine all the pieces together while the sub-items are the components you need and the money you'll get if you sell the piece individually. These are the items that you can combine together in order to get more money.
Some items are found close to each other while some span the entire game. Some of them can be combined in order to make items that will get you more money. Here are all the treasures that you can find in Resident Evil 4 and how much they will get you from the merchant.