How do Mendel's experiments show that traits are inherited independently?

Mendel performed another experiment with Pea plants, this time taking two traits into consideration, yellow round seeds and green wrinkled seeds. He crossed these two plants and in the F1 generation and obtained all yellow round seeds. Yellow and round were dominant so they were expressed and Green and wrinkled were recessive so they remain suppressed. He self-pollinated these F1 generation plants to produce F2 generation and found yellow round seeds, green wrinkled seeds. Also he found yellow wrinkled seeds and green round seeds. Thus this experiment showed that the traits are inherited independently.