pizo

One root, no seams. Pizo is a pea, and there is nothing inside it to take apart: not pi plus anything, not a shortened form of something longer. The plant is pizujo or pizarbo in loose speech, the pod is guŝo, and a whole plate of them is pizoj because Esperanto, unlike English, has never been confused about whether the singular is one pea or several.

And now the funniest fence in the chapter. Pico at rank 1398 is a pizza. Pizo is a pea. One letter apart, both of them food, both of them things you might reasonably order, and the letters that differ are z and c, which in Esperanto are pronounced quite differently: z is the buzz in English zoo, c is the ts in cats. So pico is PEE-tso and pizo is PEE-zo, and if you get it wrong at a counter in Italy you will be handed something very small and green.

Where you meet it. Peas are a stock item in the graded reader and the kitchen vocabulary alike: legomo is the category, supo is where peas mostly end up, and terpomo is the other thing growing in the same patch. The proverb-sized use is kiel du pizoj, as alike as two peas, which Esperanto borrowed straight from the languages that already had it.