(Since you used the dollar sign without any qualification, I assume you're in the United States and talking about US dollars.)
You have a few options here. I won't make a specific recommendation, but will present some options and hopefully useful information. Here's the short story:
- You don't want to start buying individual stocks with that amount of money.
- There are several reasonable mutual funds available with the amount of money you're talking about.
- Treasury savings bonds are an option. They are convenient and come with guarantees, and the government planned them for exactly this purpose. However, the rates are quite low.
- You can leave it in a savings account. This is convenient, but you probably won't keep up with inflation.
- You can buy certificates of deposit (CDs) from a bank.
To buy individual stocks, you need to go through a broker. These brokers charge a fee for every transaction, usually in the neighborhood of $7. Since you probably won't want to just buy and hold a single stock for 15 years, the fees are probably unreasonable for you.
If you want the educational experience of picking stocks and managing a portfolio, I suggest not using real money.
Most mutual funds have minimum investments on the order of a few thousand dollars. If you shop around, there are mutual funds that may work for you. In general, look for a fund that:
- has a suitably low minimal investment,
- allows you to make a custodial account for your daughter,
- has a low expense ratio (much less than 1%),
- doesn't have transaction fees (sometimes called "load"), and
- subject to taste, tracks an index (such as the S&P500) and doesn't try to be too fancy.
An example of a fund that meets these requirements is SWPPX from Charles Schwabb, which tracks the S&P 500. Buy the product directly from the mutual fund company: if you go through a broker or financial manager they'll try to rip you off.
The main advantage of such a mutual fund is that it will probably make your daughter significantly more money over the next 15 years than the safer options. The tradeoff is that you have to be prepared to accept the volatility of the stock market and the possibility that your daughter might lose money.
Your daughter can buy savings bonds through the US Treasury's TreasuryDirect website. There are two relevant varieties:
- Series EE bonds, which do not specifically track inflation.
- Series I bonds, which do specifically track inflation.
You and your daughter seem to be the intended customers of these products: they are available in low denominations and they guarantee a rate for up to 30 years. The Series I bonds are the only product I know of that's guaranteed to keep pace with inflation until redeemed at an unknown time many years in the future.
It is probably not a big concern for your daughter in these amounts, but the interest on these bonds is exempt from state taxes in all cases, and is exempt from Federal taxes if you use them for education expenses.
The main weakness of these bonds is probably that they're too safe. You can get better returns by taking some risk, and some risk is probably acceptable in your situation.
Savings accounts, including so-called "money market accounts" from banks are a possibility. They are very convenient, but you might have to shop around for one that:
- offers custodial accounts or accounts for minors and
- doesn't charge fees or unreasonably reduce the interest rate for the amount of money you're talking about.
I don't have any particular insight into whether these are likely to outperform or be outperformed by treasury bonds. Remember, however, that the interest rates are not guaranteed over the long run, and that money lost to inflation is significant over 15 years.
Certificates of Deposit (CDs)
Certificates of deposit are what a bank wants you to do in your situation: you hand your money to the bank, and they guarantee a rate for some number of months or years. You pay a penalty if you want the money sooner. The longest terms I've typically seen are 5 years, but there may be longer terms available if you shop around.
You can probably get better rates on CDs than you can through a savings account. The rates are not guaranteed in the long run, since the terms won't last 15 years and you'll have to get new CDs as your old ones mature. Again, I don't have any particular insight on whether these are likely to keep up with inflation or how performance will compare to treasury bonds.
Watch out for the same things that affect savings accounts, in particular fees and reduced rates for balances of your size.