I saw a "meme" the other day... Basically it's a single picture usually with a sentence or caption to convey a quick thought. This one showed a whole bunch of different types of flowers and most of them had an X over them because they weren't native. This was intended to tell people to plant native plants for pollinators over nonnatives. But there was no rhyme or reason to what they'd crossed out. The only two they hadn't crossed out was the New England Aster and Sunflowers, and while these were the only two natives on the list, they hardly feed pollinators adequately through the year. I'd say the earliest either of them would flower was in July.
Symplocarpus foetidus, Skunk Cabbage, is flowering out in the wetter parts of forests now but flies visit their foul smelling flowers more often than bees.
Acer sp, have also started flowering and will become the main source of early nectar in the coming weeks. Here I managed to find a common house fly pollinating the blooms on a low branch. There were a few bees about too but their images came out even worse than this one.
Willows, Salix sp, have also been flowering for a few weeks now but are only a source of pollen. Most shrubs in the genus are wind pollinated but insects can't help but collect it anyway.
So when it comes to pollinators we shouldn't be crossing plants off the list just because they're not native. The only ones that should be avoided are ones that are invasive, or perhaps double flowering and cultivated into sterility.
Native alternatives to Crocuses would be either Pasque flower (native to the mid-west) or Hepatica, but neither are flowering at this time as far as I know.