Just found the one linked, I like it but I can't find the high resolution version, so I was curious to see where people get theirs.
My lockscreen is a photo I snapped at Walden Pond in Concord, Massachusetts a few years ago. On the one hand it represents a very personal memory. On the other I just find it aesthetically pleasing, so maybe someone else might as well? Thanks for posting your favorites, by the way!
edit: this version isn't cropped right, sorry, but if you take the middle part it should fit nicely on a phone.