A gold standard just fixes the price of gold. The price of everything else would go up or down depending on the price of gold. If the price of gold went up, the value of the dollar would also go up and we would have deflation in the price of everything else. If the price of gold went down, the value of the dollar would also go down and we would have inflation in the price of everything else.
Now consider the fact that China and Russia are two of the three largest gold producing countries in the world and can flood or cut off the gold market anytime they want to cause gold prices to crash or skyrocket. I really don't think it would be a good idea to give China and Russia that much control over the value of US currency.
It is something that is actually useful and we make a lot of it.
Gold vanishes and we can get by. If wheat goes away..... well, have you ever seen the movie "No Blade of Grass"?