Hi Richard,

Sorry for the delay in replying but I wanted to consult with the EMG staff as I could not identify the plant from the photos you sent.  

We believe that this is unlikely to be an invasive plant.  However, here's the link to the VT Invasives site and you can see if anything there looks like your plant.  https://vtinvasives.org/gallery-of-terrestrial-plants

If you can wait until the leaves are fully out and then send another photo, we might be able to fully identify it for you.  It would be helpful if you can cut a stem/twig and send a photo of that as well. 

You could also look around at some nearby trees to see if the leaves area similar - birds could be bringing the seed to your yard.  "Adult" trees can be easier to identify than saplings and it might be a tree you know.

However, if you don't want to have large plants growing in that area, it would be a good time to pull them out.  It would seem they may be a fast growing plant and it will be harder to remove them as they get bigger.

I hope you do send some more photos in a week or so as I'm curious to find out what these are!   Thanks for sending in this challenge!