Myths surrounds the memory of Washington that earlier generations of children were taught in the classroom...I know I learned it there. For instance, the untrue tale about how he once threw a silver dollar across the Potomac River.
First we have to set aside the fact that silver dollars didn’t actually exist when Washington was young. The first U.S. Mint building didn't begin operations in Philadelphia until 1793, and the first silver dollar appeared the following year – the Flowing Hair dollar of 1794-95. According to the official mint report, just 1,758 dollars were struck the first year.
Next, the Potomac River is over a mile wide—it would be impossible to accomplish such a feat without the aid of some serious wind.
That being said, his step-grandson recorded a story that Washington once threw a piece of slate roughly the size of a silver dollar across the Rappahannock River, which was only about 250 feet wide near the Washington homestead; this is obviously significantly more doable.