TIL that US dimes, quarters, half dollars and dollar coins were minted in 90% silver until 1964, but this was changed to nickel and copper starting in 1965 because the price of silver had risen to a point where the coins were worth more in silver than their face value.

https://en.wikipedia.org/wiki/Silver_coin

https://www.reddit.com/r/todayilearned/comments/15lwq2v/til_that_us_dimes_quarters_half_dollars_and/