I have no idea where I found this... it was among the first of my genealogical finds online, and I failed to cite source...sorry!
Pulliam Family History Research yields no less than three possible sources for the English surname Pulliam. In the first instance, it may be of local derivation, belonging to that large category of surnames derived from the name of the place where an original bearer dwelt or where he once held land. In this case the name means "descendant of one who dwelt in or hailed from Pulham," this being the name of small parishes in the counties of Norfolk and Dorset. The place name itself means "homestead or river-meadow by a pool," and was first recorded in the Dorsetshire Domesday Book of 1086, where we read that "Reinbald the priest holds Pulham from the King. He held it himself before 1066." The place name then appeared as a surname in 1273, when one Nicholas de Pulham was listed in the Norfolk Rotuli Hundredorum (Hundred Rolls). Alternatively, the surname may be one of an even more extensive set of variants which includes Pullen, Pullein, Pulleyn, and Pullian. All of these are of nickname origin, taken from a characteristic of their original bearers, which in this case finds its source in the Old French term "poulain," literally "a colt," but frequently attributed to one of a markedly skittish or awkward nature. It was first recorded as a surname in 1166, when the Norfolk Pipe Rolls cited one Richard Pulein. Finally, where the surname is in fact ultimately of Welsh rather than English origin, it is a Welsh diminutive of the personal name William meaning literally "resolution-helmet," which comes in fact from an abbreviation of "ap-William," meaning "son of William" (the surnames Bowen and Price are similarly derived from ap-Owen and ap-Rhys). Later records include a reference to Mary Jane Pulliam, daughter of James and Mary Pulliam born in Yorkshire in 1703. American references include the birth of Agatha Pulliam, daughter of John Pulliam in Virginia in 1768.