Eating vegetables in season makes sense, because the amount of energy used to get a blueberry from a neighboring state is a tiny fraction of one flown in from Chile. Local veggies will likely taste better, too. But grocery stores don't make it easy.
The solution is a food calender, and this is the most intuitive one we've seen. Granted, it's not that good looking, but the pinwheel shows what's in season by month; the outermost ring shows what's particularly delicious at that time:
On the left, there's a a chart showing the seasonality of each vegetable (the colors represent the season):