Millions of Americans are missing out on billions in forgotten cash.

Currently, states, federal agencies and other organizations collectively hold more than $58 billion in unclaimed cash and benefits. That's roughly $186 for every U.S. resident. The unclaimed property comes from a variety of sources, including abandoned bank accounts and stock holdings, unclaimed life insurance payouts and forgotten pension benefits.

Some people are owed serious cash. Last year, a Connecticut resident claimed $32.8 million, proceeds from the sale of nearly 1.3 million shares of stock. The recipient of the funds requested to remain anonymous and no further details were provided.

More than $300 million in pension benefits is currently owed to some 38,000 people, according to the Pension Benefit Guaranty Corp. The unclaimed benefits currently range from 12 cents to a whopping $704,621, with an average benefit of $9,100. Benefits may go unclaimed because an employee is unaware they had accrued retirement benefits at a previous employer, the agency said.

However, the majority of the forgotten funds -- roughly $41.7 billion -- are held by the states, according to the National Association of Unclaimed Property Administrators.

Under varying state laws, financial institutions and other companies are required to turn over any funds considered "abandoned," including uncashed paychecks, forgotten bank account balances, unclaimed refunds, insurance payouts and contents of safe deposit boxes. They have found some pretty unusual items like diamonds, bottles of liquor and sardines. Property is usually considered abandoned after the holder of the account or property has had no activity or contact with the owner for several years.

The states then try to find the owner through websites, newspaper ads and booths at events like state fairs. But every year, the vast majority of unclaimed funds remain in state coffers, where the cash can be used to fund government operations. Although the states are careful to note that the owner's claim to the property will always remain valid.

"The money belongs to the owner in perpetuity. Even if the owner dies, then their heirs could come back and claim it," said Carolyn Atkinson, West Virginia's deputy treasurer for unclaimed property and a past president of National Association of Unclaimed Property Administrators.

Florida's chief financial officer announced this month that the state had received 61,271 new unclaimed property accounts worth more than $25 million as part of a settlement with insurance company AIG ( AIG ). The settlement is one of several reached last year with major insurers, including MetLife ( MET ), Prudential ( PRU ) and Nationwide after regulators in 20 states audited the methods they used to locate life insurance beneficiaries after a policyholder's death.

The state auditors found that many insurers would use the Social Security Administration's Death Master File to cancel annuity payments to clients who passed away, but not to start issuing payments to their beneficiaries. In some cases, companies would continue collecting premium payments from the policy's value for years after the insured's death, depleting the cash reserves down to zero.

Through the settlements, those balances are being reinstated and remitted to the states. But in many cases, beneficiaries remain unaware of their policy claim and many of their current addresses are unknown, making it hard for the funds to be connected with their rightful owner.

"Once it goes to the state, it's unlikely that the rightful owner will be found," said Mark Paolillo, a Massachusetts-based accountant and Ryan LLC's abandoned and unclaimed property practice leader.

Are you owed money? Here's where you can find out.

• State-held unclaimed property: Visit NAUPA's unclaimed.org for a map with links to each state's program.

• Life insurance: For benefits not held by the state, check the insurer's site directly. For example, MetLife has an online search .

• Pensions: For Pension Benefit Guaranty Corp. benefits, visit the agency's online search directory .

• U.S. savings bonds: More than 45 million matured savings bonds, worth nearly $16 billion, remain unredeemed, according to the U.S. Department of the Treasury. To search the database, visit treasuryhunt.gov .

• Tax refunds: In 2011, the Internal Revenue Service said it had $153.3 million in tax refund checks that were undeliverable. To make sure you've received your checks, visit the IRS's Where's my refund? tool.

• Overbid proceeds: If a foreclosed home or tax lien for delinquent taxes is sold at auction for a price above the money owed, the former property owner is owed the so-called "overbid proceeds," which are typically held at the country level. But, counties typically send notifications about the funds to the foreclosed address, so many people remain unaware of the extra cash, according to Mary Pitman, author of "The Little Book of Missing Money." These funds are different than other unclaimed funds in that the property owner's claim in some counties only last a few years. Contact the county clerk to find out which local agency holds the funds.