While I was gone over the summer my cousin was doing some remodeling in his house, complete gutting to studs and all. He discovered these inside the wall of the master bedroom. 1829 Half Dime:
In the house I grew up in, which was built in 1964, there is a set of built in drawers at the end of the hall. Underneath the bottom drawer, there was a 1964 Kennedy half dollar. She gave it to me and it's proudly displayed in my 1964 coin holder. Apparently this was the tradition back in those days.
Only thing he's not sure about is when the Jefferson got into the wall, as it was found in the same section of wall.