The funds generally yield slightly better than the current T-bill rate. This investment carries very little risk. Money market funds have lost some of their glitter since treasury bills became available to the smaller investor. These funds are generally no-load funds, which simply means that no commission is charged when they are purchased. Howeve,r there is usually an ongoing fee that is paid to the fund's management.
Management fees vary depending on the amount invested and the particular mutual fund company.
You can get your money within 24 hours plus any accrued interest. Interest is calculated daily in most funds, and compounded monthly. Most mutual fund dealers sell money market funds. A mutual fund broker can usually show you where to find a good money market fund. As well, stockbrokers sell these and some funds are even sponsored by the brokerage house itself.