Plant 1: rosaceous: the purple leaf colour suggests the commonly planted
purple-leaved variety of Myrobalan Plum, Prunus cerasifera
'Atropurpurea'

Plant 2: a maple (not an oaks - oak have catkins, not "regular"
flowers). If I saw it in the UK I'd pass over it as Norway Maple, Acer
platanoides, but the USA has a different selection of species. You might
want to check Sugar Maple, Acer saccharum_, or indeed other species.

Plant 3: Dandelion, Taraxacum sp.

Plant 4: rosaceous, perhaps Amelanchier, but I'm not good at identifying
rosaceous trees, even restricting myself to those commonly grown in
Britain.
--
Stewart Robert Hinsley