I have lots of these about and thought they were called arrowheads ferns but somebody local said they were osterich ferns and what they harvest early in springs and eat as fiddleheads...

That looks more like one of the wood ferns (Dryopteris). You can be sure it's not ostrich fern by turning over the leaves and finding the small dots (sori) where the spores come from. In ostrich fern the spores are formed on separate stalks that don't look anything like a typical fern leaves. Do a Google image search for Matteuccia struthiopteris and you'll know what to look for. The fern you are most likely to mistake for ostrich fern in PA is the cinnamon fern. Get the Peterson Field Guide to Ferns from the library to be sure. I don't think any of the ferns are poisonous (bracken may be an exception in large quantities), but many are tough or bitter. Now is the time to hunt for ostrich ferns, so you can go back in spring to get the fiddleheads. It's worth finding the right plant. It's delicious.

Alpinist-Thanks for your replys to my post[s]...this is the kind of help I need. Wish there were someone lik,e youy here where I live, great info !