On current US bills there is a statement:
"This note is legal tender"
If you have any other statement than that a collector will be interested and it's worth much more.
Sometimes even Hollywood studios will buy them for period-accurate props.
EDIT: I JUST NOTICED yours says "Will Pay To The Bearer On Demand" ( the equivalent in grains of gold )
so this note was issued when USA was still on The Gold Standard and a dollar bill was exchangeable for
a particular number of grains ( parts of an ounce ) of gold. Back then money had real value.
Now it only represents a debt that USA has to the privately owned bank "The Federal Reserve Bank"
so this note is worth more to a collector than the value printed on it - how much more depends on
the condition of the bill. I can see that this one has been folded, so, it's hard to say.
However if you want to get an idea - put the best one on EBAY ( look at how other us dollars are
listed - the things said in title and description ) and then just end your auction before someone wins
but look at the highest bid and you'll know what the market might offer.
I don't recommend selling money on ebay - chances are you'll get ripped off. Just use ebay as a test
facility to see what price you might get from a collector before you go looking.
Hey, maybe call the guys from PAWN STARS - the TV show about the pawn shop in Las Vegas.
http://gspawn.com/
They buy paper money - and I would trust sending them a FedEx package with ( a few of ) the bills
if they made an offer based on photos. I trust they'd pay you what they promised. But don't do more
than 3 at a time in case Fed Ex "loses" the package - and - don't list CASH or MONEY on the waybill.
Just say "Paper Collectables"
pretty well conserved but not like I saw in ebay on those small plastic little boxes 
