The drop between the handle and the bowl gives it away; it looks to be a pewter rat tail spoon:
That style was made between the 1710's and the 1750's although it could have been lost or discarded later.
I completely agree Max, because of the style/slope of the inside of the bowl and the length of the tail, this spoon could date anywhere from the late 1600s to the mid-18thc. This style of spoon generally dates to the 1700s and are known as rat tails. These were generally produced from around 1710 to about 1750. Rat tails can be more specifically dated based on the length of the rat tail - the longer the older the spoon. Yours find appears to be in the middle of the date range, which should date it to the 1720-40.