Poison Ivy? Nope. That little 3 leaf vine is Virginia Creeper. It is not
unusual to find 3, 4, and 5 leaflets on the virginia creeper vine. The
way to tell is that the middle leaflet does not have a longer stem,
the leaflets are more top shaped, and are sharply serrated. Picture taken
late May in USDA zone 6 (mid-Atlantic).