This is what is called a Struck Through Debris. Also referred to as Struck Through Grease. In your Quarter the letter T in TRUST on the Die was filled with some sort of foreign material. So when it struck the blank planchet during the minting process the letter T was not formed This is considered a very minor error with no value. It is very common and we have seen it many times here on CoinTalk. On eby they have been sold to people with no knowledge of what has happened for ridiculous amounts of money.
people will buy and bid the coin up to rediculous amounts. IMO it's not the error that makes the coin collectible to some but how it reads. http://www.ebay.com/itm/2005-P-Kansas-State-Quarter-034-In-God-We-Rust-034-Faint-T-Error-/232122544844?hash=item360b94f2cc:g:r28AAOSwo4pYDGjK&nma=true&si=daG8B38D1ZQ4NhnwI5cq4hpguTk%3D&orig_cvip=true&rt=nc&_trksid=p2047675.l2557
