Instruction: First, identify the target attributes from the provided list. Then, scan the product title, description, feature, and brand to extract the values associated with each target attribute. Finally, create a list of dictionaries, each containing the extracted attribute, its corresponding value, and the source where it was found.

Input:
Product title: 2010 W American Silver Eagle Proof $1 OGP U.S. Mint
Product feature: 2010-W American Silver Eagle Proof, Complete Original US Mint packaging including Certificate of Authenticity, Minted at US Mint West Point, This "vintage" Proof Set has been previously owned
Product price: $55.05
Target attributes: US Denomination
Answer: attribute: us denomination
value: american silver eagle
source: product title
attribute: us denomination
value: american silver eagle
source: product feature