I bought I-bonds in 2003 (not sure of the year now). Back then the interest was around 6%. I bought 6000, they gave me 6 1k certificates. Later I added more and changed them to online notes. I sold them in 2011 when I needed money to buy my house.
It was fed tax free. I remember I had a total of 20K+ I-bonds and received 2000+ interests (maybe 2600, don't remember now).
Since the inflation was low and the interest was very low in later years。 没吸引力了