With such a low cost & common coin like that its highly unlikely you will ever be 'had'. Its always good to know what you buy before you buy it. This coin should only cost about $1 max.
Dads thoughts:
I have an observation to make on the Roman Coin posted by Coinhound1983. I believe it is a genuine (with slight edge damage) CENTENIONALIS of Emperor CONSTANTIUS II minted between the years 348-355. Year depends on weight, size and mint site.
The obverse legend is DN CONSTAN-[TI]VS PF AVG with Diadem bust right. (It is not a CONSTANS as that emperor’s legend for this type of reverse is usually DN CONSTA-NS PF AVG). There is never a ‘V’ in Constans’ name part of the legend but as one of the other main legends often used (with a break between letters on left and right) was DN CONSTAN-S PF AVG - I can see how this coin may be taken to be that emperor.
The Reverse is a [FEL TEMP] REPARATIO type of Emperor on galley with helmsman although I am not sure whether it is a VICTORY or a PHOENIX being held due to the cleaning – it will be one or the other. It could be a number of any mints as the Exergue line is not clear but many of this type were made in Siscia up to AD355.
So a Sears(88) 4001 or 4002 referenced and relatively common type of Constantius II coin.