The wheat pennies went away in 1959, replaced by the pennies with the Lincoln Memorial on the reverse side. I remember it well, because I was collecting pennies in those days. Wish I still had my collection, but that is another story for another day.
Just did a search and the metal used to make pennies is quite interesting. From 1793 until 1857 they were pure copper.
From 1856 to 1864 they were 88% copper, 12% nickel.
From 1864 until 1942 they were 95% copper, 5% tin and zinc.
In 1943, because of the war time need for copper, most of the pennies made were zinc coated steel. It gets more interesting than that, but that's all we need to say here.
From 1944 until 1946 they were 95% copper and 5% zinc, but get this, some of them had spent brass shell cases mixed into the alloy.
1962 - 1981, they were actually made from brass, (95% copper, 5% zinc).
In 1982, because of the rise in cost of copper, the government started trying different alloys. The cost of copper had risen to about 1 cent per penny and it did not make economic sense to continue making pennies with a high copper content. So ever since 1982, pennies have been made from zinc with a plating consisting of 97.5% zinc, 2.5% copper.
The government has been trying to eliminate pennies for years, because they cost more to make than they are worth, but so far the public has prevented that from happening.
An interesting side note is the Pennies for Old Ironsides campaign of the 1920s and 1930s.
https://www.navyhistory.org/2012/08/pennies-for-old-ironsides/
Today The U.S.S. Constitution is still on view at the old Boston Navy Yard, I have been on board twice. About twenty years ago she needed new masts, the old ones were rotted and unsafe. Somebody found some old timbers in storage at the Navy Yard and new masts were made. Old Ironsides is the world's oldest commissioned naval vessel still afloat. Every year she gets taken out into Boston Harbor and turned around so she will weather evenly on both sides while at her dock. She sailed under her own power, very carefully because she is priceless, in 1997 to commemorator her 200th birthday, and again in 2012 to commemorate the 200th anniversary of her most famous battle when she defeated the British ship H.M.S. Guerriere. This battle was when she gained her nickname Old Ironsides as the British cannonballs bounced off her oak sides.
Just thought I would add that in.