I found this great tid bit about How To Buy Fresh Corn from the Reluctant Gourmet:
The most important thing to remember when buying fresh corn on the cob is that it starts converting sweet tasting sugars to starches immediately after it is picked. So ideally you want to buy it, cook it and consume it the same day it is picked or as close to then as possible. I have read that sweet corn has an 80:20 sugar-starch ratio when harvested but within 3 days that ratio will shift to 20:80. That's the difference between really sweet-tender corn and mealy tough corn.
When buying, pick up each ear and look for ears that feel full and plumb in your hand. Take a look at the silk sticking out at the top, it should be golden pale, slightly sticky, and the more the merrier.
Even though it's sometimes messy and gets all over you when shucking, the more silk, the more kernels of corn. You also want the husks to have a good green color - not brown. Even though most stores don't appreciate your doing this, try popping one of the kernels with your thumbnail. If the juice from the kernel is milky, the fresher the corn. And don't buy corn that has been sitting out in the sun all day. The sun and heat will speed up that conversion of sugar to starch.
Look at the bottom of the ear of corn where it has been broken off at the stalk. If it has already turned brown, it most likely is at least 2 days old.
If you are not going to cook and eat your fresh corn that day, store it in the refrigerator with the husks left on. Cooling it will help slow down the sugar - starch transformation. You may also want to remove the long stem and outer most big leaves to prevent loss of moisture. Will it last more than a day? Sure it will but as the clock ticks, so does the sugar/starch ratio.
So I logged onto http://www.foodblogsearch.com/ and searched for corn and found someone out there who suggest to boil them whole, without taking the husks off. That sounded easy enough. So I brought a big pot of salted water to boil and threw in my two ears of corn.
Popped the lid on and let it cook for another 10 minutes.
When I removed the corn, it was beautiful! The silk and husks were falling off.
I just loved the color of the kernels here.
My addition to this vegetable side that sent it over the top was to mix a tablespoon of Parmesan cheese with a little bit of butter, salt, pepper, onion powder and garlic powder, and pop in the microwave. It melted into this really flavorful paste.
Jim and I both enjoyed these very much.