Re: Early season stocked trout in small lakes
" ... A fly that looks like a grain pellet ? !!!"
aka Pellet Fly. More effective if you can find out what the hatchery was feeding, exact what. Dub up a pellet that mimics the stuff; watch the floating or sinking qualities and store the 'flies' in a baby food jar of the stuff. Not the most ethical of things, but very effective (and boring in 15 minutes).
I have hound that stockers like peacock herl, starling and #14 Wulff Royals. In tannic water yellows and purples are kind of important. Over tied flies seem preferred as do flies with lots of movement.
It's often hard to go wrong with a herl bodied & black woolly bugger and pheasant tail nymphs.