A 1963 $5.00 United States Note with a yellow seal?

Eric H. writes: Two questions:
1) Have you heard of any 1963 series United States Notes $5.00 denomination with a yellow seal?
2) Have you heard of any bicentennial half dollars (silver clad – no mint mark) from the Philadelphia mint?

1. Yes, this is done by treating the note with bleach. Sorry, no cigar.

2. U.S. coins prior to 1981 do not have a Mint mark if they were struck at the Philadelphia Mint (an exception is the War Nickels from 1942-1945).