Where are you? Most of the time, if you can find them, they can probably go outside in the summer. I have the name of one on the tip of my tongue, if it comes to me, I'll post it.

I'm somewhere in the middle of Ohio. Or in the northwesternish middle part, anyway.

I've heard the named blechnum gibbum tossed around a bit. I've also heard that bird's nest ferns can form trunks, although most people apparently grow them low so I doubt I could actually buy one with a decent trunk on it.

Dicksonia Antarctica (I think?) is the other one I'm familiar with. I've seen it in person and I think it's pretty neat, but I definitely have never seen that in my area.

Do ostrich ferns form trunks at all? Actually, I'm not sure it's an ostrich fern as the spore-bearing fronds look different, but the way the crown on these things I have in my yard gets, it looks like they might form a bit of a trunk.

Anyway, I live in a dorm most of the year, and while the dorm is sort of dry, it also has no air circulation at all so it's pretty easy to hike the humidity up really high without much effort.

Cibotium schiedei 'Mexican tree fern' grows well as a house plant. However, it's a little hard to find. Though I believe the Fern Factory currently has them. http://www.fernfactory.com

I'll keep an eye on that one. I've realized, doing some research, that some kinds of tree ferns are more available than I thought. They're just not really being clearly marketed and labelled as tree ferns