Presidential dollar coins have proven to be nearly as popular with coin collectors as the 50 state quarters have been since they were first released in 1999.

While many people go to their nearest bank to pick up the latest designs coming out for the Presidential dollars, there is another way to acquire beautiful examples of these medal-like legal tender coins honoring our nation's former, deceased presidents: proof sets.

If you're collecting U.S. coins, you might feel a little limited in terms of what you can collect. After all, it seems to some collectors that there is just not a lot of variety in U.S. coinage.

However, there really is a lot of diversity in U.S. coins. In the United States' more than 200 years of coin production, our nation has seen many types of interesting coins.

If you find yourself a little bored with "typical" modern U.S. coins, then consider these 5 unique types of coins worth collecting.

Gold...

...it led thousands to San Francisco late in the 1840s

...it's what the fabled Rumpelstiltskin made from straw

...and it's the metal that has been the material obsession of many for years.

Gold coins were once the standard of commerce for many nations -- including the United States. Today, gold remains one of the most popular bullion (precious metal in bulk form) investments.

The United States has been striking gold coins since 1795, and struck its last gold coin intended for circulation in 1933.

After a hiatus of many years, the United States began striking gold coins again in the 1980s, when the U.S. Mint started striking commemorative coins.  It was also during this time that the U.S. Mint first offered official "bullion" coins, minted in highly pure, exactly measured increments of gold (also silver and, more recently, platinum).

You may have heard about Buffalo gold coins.

You are probably asking if they're anything like Buffalo nickels. Most importantly, you want to know what they are worth, right?

First, know that Buffalo gold coins are officially known as American Buffalo gold coins. They are the very first 24-karat gold coins the U.S. Mint has ever produced. The 24k American Buffalo is a coin that is made from .9999 fine (virtually pure) gold.

 

Mintage numbers are something that coin collectors must become well-versed in if they are to understand part of what makes a coin valuable, as well as what helps to make a coin rare.

The mintage number of a coin simply refers to how many coins were struck by the mint.

It does not, however, necessarily refer to how many coins still exist. After all, there are many coins which, over the years, have been minted in great quantity -- only to be later melted down or destroyed, either by the mint or by private interests.

There are also many coins which have inevitably become lost to time, either through burial or corrosion. There are also countless coins which have been lost through disposal, which can happen unintentionally or purposefully.

Therefore, a mintage number essentially acts as a means to help one understand how many coins the mint actually made.

It in no way solidly tells us how many coins of a given date or mint mark may actually be left, though there are any people who have estimated such numbers.

When I began collecting coins, one of the first goals I set for myself was to construct a twentieth century coin set.

What is that? Quite simply, a 20th century type coin set is a collection of coins which includes one of each design from each denomination the United States produced between 1900 and 1999.

Many people look to their pocket change with interest.

Why? Because coins, which are at the root of our nation's -- and the world's -- economy, offer so much more than buying power. They represent history, society, geography, and politics in artistic designs meant to capture the eye and, often, the imagination.

Following are some tips for setting goals for your own coin collection, no matter how large or small it might be (...even if you never really thought of yourself as a "coin collector").

The Susan B. Anthony dollar coin has all the hallmarks of becoming a highly sought after collectible.

It is often referred to as the Carter Quarter (the Carter administration promoted it with a vengeance, calling it "the dollar of the future"), as well as the Anthony Dollar, Susie B, SooBee and SBA. 

Calling it the Carter quarter made reference to the deterioration of the value of the dollar, plus it emphasized the fact that it was being confused with the quarter and that it was conceived on president Carter's watch.
-- Philip Diehl (former director of the Mint who oversaw the coin's launch)

With a short run and high numbers minted, Susan B. Anthony coins still show up in pocket change these days.  For the beginning coin collector, what better way to start a fun collection than with loose change that happens to have an interesting history?

Now here's a fun gift idea for anyone who likes coins...

Thinking about dabbling in coin collecting?

Have a few interesting coins that you found in your pocketchange and now you're wondering if they're worth holding onto?

If you were going to keep a small collection of coins, which ones would they be?

While there is no single answer that defines the "best" coins to collect (because everyone has a different opinion as to the best coins worth holding onto), here are some ideas and opinions from others who collect coins. See which coins they've chosen to collect and why they. Hint: They're not all rare U.S. coins.