You'd have to find a farmer with a field who would let you pick it fresh off the stalk. In Cuba we cut off the corn kernels with a grooved piece of wood with a blade in it. Use sweet corn. The masa flour tends to dampen the sweetness. The difference in taste is very slight.
Some beginners make the mistake of using too much meat or meat that is in large chunks.
A good tamale will be riddled with tiny flecks of meat. Grind the corn in a food processor until you get a coarse mixture. Remove from the processor and blend in one cup masa harina and one cup water to the ground corn. We've had good luck with de-boned pork ribs. Or have the butcher cut something to order.