That's really interesting.
It might not be your primary focus, but I see that on the National Library of Scotland digital maps site, the Ainslie map of 1796 (which seems to be the first mention) calls it "Shoolbread" and then a map of 1826 calls it "Schoolbread". However, in the 1850s, Ordnance Survey called it "Shovelbread". In my experience they were pretty thorough, to the extent that they would overule a powerful landowner's view in favour of local tradition so there's every chance that's the authentic "original".
I see there was also a a "Shovelbread Dam" at that time from the 6" map so it strikes me as pretty likely that if you were interested in following it up, there might be an explanation for the name in the Ordnance Survey Name Book for the parish of Houston, assuming that can be had in the West Regiuster House in Edinburgh (Sorry it's been a while, but that's where they used to be...).
[Edit] Forgot to say, the very point that caught my eye - What's really interesting though is that "Shovelboard" or "Shuffleboard" is a game played by pushing pieces along a long table. I wonder if it might once have been an inn... };-)
