What about potato seeds?

What about two potatoes?

What about a poutine?

French Fries used to be potato, but now they are fries. Inside the oil, they are neither fry nor potato, but a secret third thing forbidden to you.

Objection: Sweet potatoes.

Their name says they're clearly potato, but:

Sweet potato is only distantly related to the common potato

Source

https://www.youtube.com/watch?v=ACmydtFDTGs

Thus kind of joke always reminds me a mathematics joke, for this instance we're using potatoes.

Everything in the universe is either a potato or not a potato. The great majority, by far, is not a potato, but at the same time, the majority of things that are not potatoes, when examined very very close, or in really short time intervals, they behave as potatoes and you can use potato techniques on them.

Together, we can fix this.

Many things once were or someday will be potatoes too.

... My son said: "I'm a potato."

He's clearly not a potato. I'm not a potato. We don't current have potatoes in the pantry. The picture may be of a potato, but a picture is not a potato.

I am a sad potato