I'm interested in starting a coin collection. What coin should I start with.?

The basic rule is buy the book before the coin. There are all kinds of ways to collect so you need to go to a dealer and look at what is available. The Silver Eagles are more of a bullion coin than a collectible, except for the proofs. If you like history you can go for historic coins. If you want to be able to put a set of something together the Jefferson nickel set in mint state can be put together without going to the poor house. Most series has one or two key coins that stop a lot of people from finishing the set do to the expense. A thing that is becoming more popular is a type set. A 20th century type set can be done but an 18th century has some expensive coins especially in higher grades. It depends on you so look around and see what is out there and what you would like to have or accomplish. there are lots of coin collectors but very few numismatist. Yes they collect coins but also study hem and know the history behind them. Good luck in your endeavor.