This is my favorite knot for Flathead fishing, this knot is very reliable and I've never had a problem with it, here are step by step pictures to tie this knot.
Begin by taking a hook and run the end of the line through it to about a foot beyond the hook.
Next step is to take the end of the line back thru the eye again, go about a foot beyond the eye.
Next step is to take the line and make a simple overhand knot and pull it down loose on the hook
Next pass the hook thru the overhand knot and wet it down and pull it tight.
Pull it down tight, trim off the tag line and your in business, the more you pull the tighter it gets.
Enjoy and I hope you catch a big one............Doc Lange