Hi, 

Thank you for your question.  

Although it is hard to make a definitive ID from the photos, it appears to be a white ash tree (Fraxinus americana).  The white ash is native to the Eastern US.  These trees will grow  about 1 to 2 feet  per year reaching  50 to  100 feet in height and 40 to 50 feet in width. They grow into large shade trees. In the fall, the leaves have brilliant color in shades of red to purple. The White Ash produces purple flowers in the spring that become 1- to 2-inch  long samaras (single seeds), surrounded by papery wings.   Ash trees benefit wildlife. Many birds and small mammals eat the seeds of ash trees and because the trees tend to form cavities they serve as nesting sites for a variety of woodpeckers. Ash trees also serve as hosts for insects including the swallowtail butterfly.

It should be noted that  ash trees are continuing to decline int he US due to the Emerald Ash Borer(EAB)  an invasive jewel beetle.   As of 2022, monitoring data from the National Capital Region Inventory and Monitoring Program indicate that there are fewer than 56,000 surviving ash trees remaining in the region.

If the seedlings are small enough you may want to consider moving them to a desired location during late spring to mid summer, but be aware that these trees are highly susceptible to the Emerald Ash Borer.  If you would like to delve deeper into positively identify the trees here is a link to VA Tech's Dendrology site.

Christine