Haven't figured out the menu in-game either, but if yer willing to go the cheat route, save editing is rather simple:
Dig up a tile, make sure it's the only empty tile on the map, save. Open the save file with Notepad or something similar, search for "Empty" (with the " "), and it will jump right to it. Then find the field "status effects" shortly after the "Empty" tile designation, that's where all these resource effects go.
Dunno if there's more, but I've found these: "Mineral Rich Area"/ "Mineral Poor Area", "Fertile Area"/ "Barren Area" and "Inspiring Area"/ "Uninspiring Area". Enter whatever you please in the "status effects"[] field, ie like this: ["Mineral Rich Area","Fertile Area","Uninspiring Area"].
Note that iffen you slap multiple effects on one tile, every one of those will influence production, even if negative on it's own and seemingly unconnected. As in, build a gold mine on a ["Mineral Rich Area","Barren Area"] tile, you will get double the yield as compared to a square with only the ["Mineral Rich Area"] benefit. Add any of the "Inspiring" on top, yield is even tripled.
EDIT: Mucked around with the cheat menu a little bit, resources on tiles are not covered in that. Messing with those requires save editing as described above. The "resources" you can add with cheat menu are just the 3 displayed in the top right: Research, Money & Crystals (the ones from altar buildings).