This is a remix, combining three elements...

ThinkerThing's Open Board Game. Grass Surface Brick - https://www.thingiverse.com/thing:739034
for the sizing of the tile, and
https://www.thingiverse.com/thing:32962
and also
https://www.thingiverse.com/thing:43086
into what you see here.

Check out the single base that started this all, here: https://www.thingiverse.com/thing:6292937.

As mentioned elsewhere, you may choose to sand down your tiles to get them to fit inside the lip confines. They do make a satisfying POP/click sound when they do, and they won't go anywhere when snug in!