It's been a tradition for me to hit stocked "open" water on opening day. So, for freshly stocked trout in a stream that is probably flowing pretty well and slightly stained, fifty degree range....
The same stuff mentioned in earlier posts: junk flies and generic nymphs. A favorite of mine, esp if the stream has a lot of stocked brookies, would be a white marbou muddler fished dead drift then stripped. Have some technical flies with you as you may see a hatch. A few years ago there was a blizzard of caddis on opening day and I had a blast catching fish on dries while bait guys went skunked. However, most years, it's low and slow with something that gets their attention.