Where can I sell a 1898 nickel?

Retail prices for an 1898 nickel* range from about $3 to $35 depending on condition. You'll be lucky to get 2/3 of that amount if you sell it, because the buyer will pay wholesale.

If there's a coin show in your area (check the local papers) you might be able to sell it to someone who has a booth with a spread of U.S. 19th-century coins. Alternately, check for a dealer who has PNG or PCGS certification.

(* please, not "your" nickel. When we read it that means one of us has the nickel, LOL!)