From Stardew Valley Wiki
|Looks like it belonged to a postman or policeman. Either way, it's still very soft and smells okay.|
|Achievement Description:||Catch 24 different fish.|
|Sell Price:||Cannot be sold|
It may be a reference to the recurring character Harris from Harvest Moon, as in Harvest Moon 64 he was the town's mailman, and in Harvest Moon Back to Nature and Friends of Mineral Town, he is the town's policeman.