I remember having a "Farm Tarot" listed in my "ideas notebook" some time ago - but those had people in them.
Anyway, how about for the Wheel of Fortune, either you use a millstone (gives that old feel - plus i think in either the Gran Tarot Esoterico or the Spanish Tarot, the Wheel of Fortune card has a bear rolling a millstone). Or, for a livelier feel, you can have barn mice engaged in various activities (like the ups and downs in the wheel card) when the lights are out. A nice, big, spiderweb in the barn's beams would also be a good alternative.
For the Star, how about an image of those barn hex signs (hexagrams, but they have superstitious undertones), and to incorporate your water element, you can have the hex sign in the BG while in the foreground maybe a bird (which is also in the star card) drinking water/dew from a leaf. Or a pig wallowing in the pigsty for cheek. ha ha
The tower could be a pile of autumn leaves being burned, with critters (that got in the pile) fleeing.