Nickels

Why of course. Also, note the rising cost of all metals so start saving pennies, dimes, quarters, halves, dollar coins also. Save as many as you can. Pile them up everywhere and keep on saving them. Now in about a hundred years when the government lifts the ban on melting our coinage, you can melt all your coins and turn them in for vast amounts of cash.
Me, I'll just put the same amount in the stock market and the same again in my savings account. We can compare in a few hundred years.
Obviously I am being a bit sarcastic. Don't save stuff that will not be worth the room you used for storage.