Virginia Tech has a very nice interactive website for a question such as this: http://www.fw.vt.edu/dendro/dendrology/map/zonemap.cfm Just click your cursor on the state of interest, and you'll get back a list of all the trees, shrubs, and woody vines known to occur in that state. In front of each scientific name in the list, there's a color-coded diamond. If the diamond is green, it's a native species. If yellow or red, it's an introduced species. Pennsylvania has 309 total trees, shrubs, and woody vines listed, and there are quite a few that have been introduced. You should find several to choose from.
If you just want something that was introduced as a food or ornamental tree, ones such as apple, pear, Chinese chestnut, Norway maple, Norway spruce, Colorado blue spruce, or European mountain ash would all be good choices. If you want a species which is considered a nusiance species/invasive species, there's tree-of-Heaven, common buckthorn, or royal Paulownia.
You can google the name of the tree you choose to get more information about it.