This is what I've found in my front yard, drive way and back yard; on many occasions I can hear them hit the roof!
At least the pink golf ball comes via a couple of grandmothers or moms with two little kids playing golf. I saw at least one of the kids using the pink balls. Now mom or grandmother wasn't playing but the kids were. So grandma, teach them how to be responsible! Not destructive of other folks' property by lobing golf balls into their front yards!