Depending on where you live, and if the main stem is square. it sounds like a cup plant. It is native in the midwest. I have one growing in my yard. They are from the mint family and they are carnivorous. They trap bugs in the junction where the plant leaf starts and the main stem. It acts like a cup and holds rain water. bugs get trapped in them and the plant digests them like a venus fly trap. The flowers will fall off and the bud is left full of seeds. it will grow back each year, but they can spread into a nusance. bees like them yellow jackets in particular.