Microphyla is not a walnut species. Microcarpa is and is common in Texas. Black walnuts are a group of species in Juglans, see section Rhysocaryon. Juglans - Wikipedia
Yes, some pecan varieties can self-pollinate. It is usually protandrous varieties though a few protogynous varieties such as Mahan have been known to self-pollinate. See the pecan pollination spreadsheet for varieties that overlap. Pecan pollination chart If you can’t open the sheet, try pasting the URL direct into your browser. Filesize should be @1.3 MB. http://www.selectedplants.com/miscan/PecanPollination.xlsm
Creek, Jackson, Jubilee, and Davis are varieties noted for overlap.