Rotten Plant (748) is an unobtainable trash item that players cannot find through normal gameplay. It resembles a wilted flower or a piece of seaweed and is intended to be a placeholder or a developer's tool for testing. If it were to appear in a player's inventory through unconventional means, such as modifying game files, it would serve no practical purpose or function and could not be sold or used within the typical activities of farming, crafting, or gifting.
The item ID for Rotten Plant (748) is 748
This ID will work on PC/Mac (Steam), PS4, PS5, XBOX One, and Nintendo Switch.
Spawning items in Stardew Valley is a little unsual and is not done with commands. You will need to utilize what is called a cheat to set your character's or animal name to the item id. To do this you cannot use just the item id, you will need to surround the item id with brackets. Ex. [748]
Spawning Using the Animal MethodTo spawn Rotten Plant (748) while using an animal, you will need to head over to Marine's Ranch and purchase an animal. Once you have have an animal chosen, name the animal with the item id with brackets like this [748] and you will receive the Rotten Plant (748) item. This method can be done using an existing character and is convenient but will cost some gold every time you want an item.
Spawning Using the Character MethodTo spawn Rotten Plant (748) while using a character, you will need to create a new character and name it with the item id with brackets like this [748]. You will then receive the Rotten Plant (748) item when you speak to a villager. This method is easy and free but cannot be performed on an existing character and you will be stuck with that name unless its edited.