Question
Thank you for your expertise!  I found some flowers growing in front of our house.  I think they are some kind of morning glory, but I'm not sure what kind.  I've posted three pictures on flickr, http://www.flickr.com/photos/34202721@N00/210488200/

They are mostly white, but purple in the middle and around the edges.  We live in the middle of Pennsylvania.

I hope this is enough information, if not, please let me know.

Thank you very much!

Answer
The Morning Glories (Ipomoea sp.)are alien garden escapees; Field Bindweed is an introduced (Convolvulus sp., alien) weed.  The native Hedge Bindweed is very similar.  Your flowers look like they might be a natural hybrid because the Bindweeds do not have that much color to them, but I do not know whether the two actually will cross.