Ask Mr. Smarty Plants

Assuming you want information about lawn grasses, the article, Turf Grass Species for Pennsylvania from Penn State College of Agricultural Sciences is an excellent source of information for lawn grasses in your area.  It is obvious that they have done lots of research and provide detailed information about hardiness, diseases, fertilizing and much more for several lawn grass species.  Many of the species they talk about are introduced species but they do list a couple of native grasses.  It should be noted that those two native grasses also have introduced varieities.  Since our mission here at the Lady Bird Johnson Wildflower Center is "to increase the sustainable use and conservation of native wildflowers, plants and landscapes," I won't be recommending that you plant non-native grasses.  That doesn't mean that the introduced species are necessarily bad—it just means we hope you will consider planting native species.  The two native species recommended in the article from Penn State are:

• Poa pratensis (Kentucky bluegrass)  Here is more information from Missouri Botanical Garden.
• Festuca rubra (Red fescue)  Here is more information from Missouri Botanical Garden.

Here are some very wise tips from the Pennsylvania Department of Environmental Protection for maintaining your lawn no matter what grass you decide to use. 

If you are looking for grasses for meadows or fields or for ornamentals in your garden, you can go to our Native Plants Database and select "Poaceae (Grass Family)" by scrolling down the list in the Family: slot.  This will give you a list of all grasses in our Native Plant Database, but you can use the NARROW YOUR SEARCH option to limit the list to Pennsylvania grasses by selecting your state from the Select State of Province slot.  You will then have a list of 164 grasses native to Pennsylvania that you can scroll through, many with photos.  You can use other criteria (e.g., Light Requirement, Soil Moisture, Height) to narrow this list even further.