The Notes with the 1882-1908 dates are known as "date back" notes, but these
were issued only
in denominations of $5 and up (2nd charter period) so you are in error if
you mean that these are "dollar bills"
However they are worth MUCH more than $15 to $20 each, so if you know who
is selling these, PLEASE
have them contact a member of an organization called the Professional
Currency Dealers Association
here: http://www.rarecurrency.net/pcda_state_directory.html