High yield savings accounts are great if you’re saving up for something big and for your emergency fund. Although the yields are lower than investments, these accounts are usually FDIC insured, so you can't lose money.
Certificate of Deposits (CD) are closely related to the savings accounts but have higher interests. The FDIC also insures Cds. That means they are practically risk-free.
The disadvantage is that they aren't very liquid.
US savings bonds have one of the lowest investment risks. The US treasury issues the securities to fund the government’s operations. Saving bonds have a fixed rate of interest.
Money market accounts are closely related to savings accounts and CDs. They often have a better rate than the savings accounts but have more liquidity than CDs. The only risk is that they generally aren't FDIC insured.
Municipal bonds are loans issued to local governments by investors. These are usually a good option for better returns with slightly higher risks than savings accounts, CDs, or saving bonds.