Look at roslynnursery.com online catalog. They have an extensive list of the plants you are seeking and many other shade tolerant perennials, shrubs and trees. I have ordered from them in the past, with few problems and the servive was exceptional.
Rb

There is a nice site, from what I've seen ,very nice online and print catalouge, Sublight Gardens, they sell lots of wildflowers and they sell a nice selection of ferns and other woodland plants your would see in East Coast native forests, perfect for New York ^^
no lady slippers though, they go against that.....

Here is a link that might be useful: Sunlight Gardens

www.prairienursery.com or
www.ionxchange.com

Try Gardens of the Blue Ridge. I would look at gardenwatchdog before you order from Roslyn nursery, they have some very bad reviews lately. I bought some perennials from them 3 years ago, alot of misidentified plants and they were poorly packed. There are better sources out there. Sunlight gardens has great plants. They don't carry any trilliums. Good luck!

Hi, Lisa. I *just* got done responding to the previous post about where to get reasonable, good quality jack-in-the-pulpit and, i'll give you the same recommendation as i gave molly...try gardenweb.com's plant exchange forum. i've had such great luck with it - the plants are usually WAY better than you'll get with mail order places and all you pay is for the shipping (and, whatever you arrange to trade). usually, i end up trading something that i have too much of (compost filler as far as I'm concerned) and i get something that i want. i'll have ferns this spring. I frequently see columbines on that forum....i've never seen triliums but, you can always do a posting and see what happens.

good luck!

I haven't ordered from them (yet), but Arrowhead Alpines seems to have a good reputation here on Gardenweb. They have an incredible selection and the prices seem fair.

Shelley

Here is a link that might be useful: Arrowhead Alpines woodland plants

I have ordered from Niche Gardens in North Carolina... good service, good plants. Natives are indicated.

Here is a link that might be useful: Niche Gardens

I like munchkin nursery. I also like Rock Island Wildflowers. and We-Du now called Meadowbrook.

I worked for Phil Waldman at Roslyn Nursey a lo-ong time ago. My mom always taught me "if you can't say something nice, don't say anything at all" sooo......

I can second the referal to Nichegardens. Some plants may not be hardy in your area, so check closely.

I have bought from Munchkin Nursery and been pleased.

I have a friend who cultivates and sells wholesale. In fact one of his azaleas is listed at Rosylyn's, mentioned above. Most of his plants are for a Southern climate. But he's at www.doddnatives.com. You should ask your nursery to look into his offerings. You cannot buy through his site but it is a good resource for a picture and description of various cultivars.

Another resource I have used with success is www.plantdelights.com.

Again, these are mostly more Southern. BUT not all. They've got a great selection of hostas which won't grow in my region at all. PD nursery gives a thorough description of each plant including its origins. Not all are native but a good number are.

CN

Make a pilgrimage to New England Wilflower Society's garden in the woods (Massachusetts)... not only for inspiration, but shopping galore. It is well worth at least a two-day visit.