Coins (mostly nickels) serve several symbolic purposes. Ally first sees coins as a straightforward symbol for Grandpa and Dad, who introduced her and Travis to coin collecting when they were very young. Collecting coins is a way for both Ally and Travis to connect to their deceased grandfather and deployed father, thereby remembering the importance of their familial connections. However, it takes much longer for Ally to see that because of the nature of coin collecting, coins can also act as representations of the importance and the value of diversity and difference—after all, as Travis and one pawnshop salesman point out, coins are only collectible when they're some combination of rare, flawed, or somehow different than their brethren.
Coins Quotes in Fish in a Tree
“Well,” the guy says, “if you know anything about coins, you know that a coin with a flaw in it is far more valuable than a regular coin.”
Something isn't right with it and it's worth more?
As I walk back to my seat, I think of how when Dad left, he said that when we look at the steel pennies, we need to remember that we are unique, too. And also, that things will go back to normal for us—that he'll be home before we know it.