Bonds, get the top rated general obligation backed so the entire city has to go broke to get out of them. Beware lower rated, or non-backed, or those subject to ATM tax these days.
You can get about 3% with careful shopping, and they are tax free so that can get you close to 5% effective return.
You can resell them if you need the cash - not for short term, but if you gotta have the money, or need it in 5 years, you can get to it, they will go up or down in hard value as interest rates go up and down, but are about as safe for as high a return you can get these days. Harder to find, as others are turning to them too.