AA is within their rights (the airlines have pretty much written the rules that pertain to them - Warsaw, Montreal are the catchwords,) to request receipts or proof of ownership. BE sure to read all the terms and conditions about lost baggage... including

"Baggage Liability
Domestic travel is defined as travel in which the itinerary remains within the U.S., including Puerto Rico and/or the U.S. Virgin Islands. American Airlines and American Eagle will reimburse up to $2500 per ticketed domestic customer for lost or damaged checked baggage, subject to claim verification. The specific procedures for making lost or damaged baggage claims will be provided to you at the time a claim is filed. We will not pay for normal wear and tear on checked baggage or for loss or damage to belongings you carry on board in the passenger cabin. Certain items (e.g., cash, jewelry, cameras) are excluded from liability for lost or damaged checked baggage. A complete list of the limitations and exclusions is in our conditions of carriage and is available upon request. International travel is defined as travel in which the itinerary contains one or more segments of travel outside of the U.S., including Puerto Rico and/or the U.S. Virgin Islands. We will reimburse up to $9.07 per pound, up to a maximum weight of 70 pounds per checked bag (a maximum of $634.90 per checked bag). This limit may be lower for additional pieces to certain international destinations or when using connecting carriers.

Helpful Suggestions

Federal regulations require that checked baggage remain unlocked. Improperly packed items (e.g., boxes) or those considered fragile (e.g., paintings) may not be covered under American Airlines or American Eagle's baggage liability provisions. If the value of the contents of a checked bag exceeds our standard coverage ($2,500 per passenger for domestic travel, and $634.90 per checked bag for international travel), you may purchase additional baggage insurance. This insurance, known as excess value coverage, may be purchased at the ticket counter when checking in. Excess value insurance does not cover damage. Not all high value items are covered by this insurance, so you should verify with the agent that your specific belongings are included."

Good luck... and be glad it was a US wedding, not international.

BTW, we always do put a copy of our itinerary just inside the suitcase, since I have seen luggage tags and destination tags torn off in airports.

Here's where those wedding photographs may really pay off!