The two I do remember (this may give you an idea of the time period) are 51 Sycamore Lane and The Ghost of Windy Hill.
The third one... I cannot for the life of me remember its title. I remember bits and pieces of the book, though. I remember it involved a teenage boy coming out to the country to live with a cousin(?) for the summer. The boy has glasses, and pushes them up on his nose a lot. There's a murder mystery undercurrent, but it was all a misunderstanding (the boy had a nosebleed and lay with his head over the bank of a creek until it stopped, and someone saw him and mistook him for a murdered body) and in the end the boy and his cousin put together a big rodeo-type event to help raise money (?) for something (?) and they use sheep in the roping contests.
I know it sounds really stupid, but it was actually a pretty good book from what I remember. It would have been published probably in the late 60's or early 70's.