Flowers image of Taiwansese (Photinia serratifolia.) https://www.alabamaplants.com/Whitealt/Photinia_serratifolia_page.html

Second link for Taiwanese photinia. http://www.bio.utexas.edu/courses/bio406d/images/pics/ros/photinia_serratifolia.htm

Another possible ID is perhaps the Taiwanese photinia (Photinia serratifolia). Check out these links for their leaves, stems & branches closeup. Although I’m leaning toward the former suggested ID, not having the plant in person; I could be wrong. Comparing the back of the leaves for both genera and see either of these match. Click on images to enlarge. Best wishes! https://www.eddmaps.org/distribution/point.cfm?id=2019899

Link to Agricultural Extension Service for Maietta, GA http://extension.uga.edu/county-offices/cobb/agriculture-and-natural-resources.html

Scroll down for leaves images of Prunus caroliniana. Click images to enlarges. https://www.forestryimages.org/browse/subthumb.cfm?sub=6919

Appreciate these follow up great photos! To my eyes the details of leaves & bark are still similar to those of Carolina laurelcherry. These specimens are not be mature enough to produce flowers & fruits. I don’t grow these and can’t tell how many years for P. caroliniana to mature enough to flowers. Check out images of bark & leaves on these link to compare. Again with out flowers to confirm, this is only a suggested ID Perhaps you should take some of these saplings to the local Agricultural Extension Service for ID. Best wishes! Scrolling down to the images trunks & barks. http://www.carolinanature.com/trees/prca.html

Maybe Chinese Elm? https://www.google.com/search?q=chinese+elm+leaves&tbm=isch&ved=2ahUKEwjpgoKA6sPhAhXLhlMKHXwwCBwQ2-cCegQIABAC&oq=chinese&gs_l=mobile-gws-wiz-img.1.0.35i39j0i30l4.2502.9913..11879…2.0..1.236.2134.17j2j2……0….1…….5..35i304i39j0i13i30.RUMjVPplbW8&ei=j_2sXKn_BMuNzgL84KDgAQ&bih=718&biw=412&client=ms-android-verizon&prmd=isnv