Take a closer look before you dump that handful of pennies and nickels into the tip jar — you don't need to find a Revolutionary War-era coin to make a fortune from your change.

They're harder to find each year, but there are several valuable coins floating around that aren't all that old. They're often valuable for vastly different reasons — like the World War II-era coins minted from atypical metals, or double-printed pennies — but each one is easy to miss if you're not paying attention.

Check out these eight coins that are worth a lot more than their intended value.

1. 2004 Wisconsin state quarter with extra leaf

Find an average Wisconsin state quarter from 2004, and that will get you one-fourth of a bag of chips. Find one with either the high or low leaf error, and you can get a whole lot more.

The 50 State Quarters series ran from 1999 until 2008, with special designs representing each state. Wisconsin's quarter came out in 2004; the reverse design features a cow, a wheel of cheese and a partially husked ear of corn lurking in the back.

It would be too easy to make a corny joke about this coin. Too cheesy?

However, some the coins have an extra line below the front left leaf, which looks like another leaf entirely. There are two varieties you should be looking out for: the high leaf and low leaf.

2. 1995 double die penny

This penny has a double-printed obverse (heads side) that makes the "LIBERTY" and "IN GOD WE TRUST" look blurry. The error has happened before, in 1969 and 1972, and those versions of the coins are much more valuable.

3. 1942-1945 silver nickel

During World War II, the United States needed to save as much nickel as possible for military uses. Consequently, it started minting nickels made of 35% silver. Melting down pennies and nickels is a federal offense, but the coin might still fetch you enough for a decent lunch, if it's in good condition.

4. 1943 steel penny

Pennies were made from steel in 1943 only.

Pennies were made from steel during wartime, for the same reasons nickels were made partially from silver — steel pennies helped preserve copper for World War II. However, the switch only lasted one year.

5. Ben Franklin half-dollar

Easy to notice, but hard to find. Image: United States Mint

In 1948, the U.S. mint began circulating half-dollar coins with images of Ben Franklin and an eagle — which is funny, considering Franklin opposed the bald eagle's nomination as the nation's bird, in favor of a wild turkey.

Franklin's portrait on the coin was replaced by John F. Kennedy in 1964, following the president's 1963 assassination.

6. 1932-1964 silver quarter

Between 1932 and 1964, quarters were 90% silver and 10% copper. These silver quarters look like any pre-state quarter 25-cent piece, but are worth a lot more if they're in the right condition.

7. 'In God We Rust' 2005 Kansas state quarter

Remember: Always clean your machine. Image: About.com

While it might seem like a mint employee's rogue political statement, these coins are actually just the result of grease preventing a clean pressing.

8. Presidential dollar coin with lettering errors

These Washington dollars are missing key inscriptions. Image: NGC

In 2007, the U.S. Mint began printing a series of dollar coins featuring presidents. Many of the early coins, especially those with George Washington, have errant or missing lettering along the edge of the coin.