Not sure what you mean here, only soy plants contain soy. However, many plants do contain phytoestrogens, which can affect your hormone levels if you eat enough of them. Both sunflowers and flax contain some.
However, since most plants contain some amount of them, what matters is the dose of phytoestrogens that you are ingesting. In other words, just don't go crazy with foods that contain high amounts of phyto-e and you should be fine.