Leaves are only one part of the things needed to identify a tree. Luckily, many trees have fairly uniquely structured leaves.
I can tell you that the first leave most likely comes from a Katsura tree, which is Cercidiphyllum japonicum. These are lovely trees, so you're lucky to have that one.
The second one could be some kind of dogwood, but not sure without seeing more of the tree, like the shape of it, the bark and so on. Sorry.
The third one looks like some kind of maple, such as Acer tartaricum or Acer ginnala, both different types of Amur maple.