I have had this plan in my yard for the last 2-3 years. I think it came over from the neighbors yard. luckily if i let it poke its head taller than my grass it is easy to see. like you said you have to check your yard and beds every other day, it just seems to shoot up from nowhere.
Katrn, I hope you begin to allow this important source of food for monarch caterpillars to have a place on your property. Once the caterpillars clean off its leaves and go find a woody stem to form a chrysalis from which they'll emerge to spread their wings and fly south to Mexico, you can cut off the stems at the ground. They arise from roots in spring. The secret is to encourage them where they can climb a fence or shrub or tree or put up a TALL trellis for them. Otherwise the isolated ones will never flower or produce much foliage for the monarch caterpillars.
Fayetteville, Arkansas, is encouraging homeowners and even commercial and industrial sites to make their property eligible for certification by the National Wildlife Federation in order to be an official urban-wildlife habitat community.