I don't know anything about the origins of this small sundial, but I really like it! I'd guess it was once mounted on an outdoor wall somewhere, as there is old grout around the perimeter, just inside the edge of the tile. The tile itself I believe is transfer decorated, and the arm of the dial (called the gnomon) I am pretty sure is copper--and both are in excellent condition. While it could surely be re-inset into a wall as a permanent fixture, I'd just probably adhere a hanger to the back and hang it on a surface facing the garden, and think it would be especially great with ivy growing all around it!
The tile and gnomon are in great condition. An lip of grout around edges as pictured. 6 3/8" tall and wide, about 1 1/2 deep from tip of gnomon.