I have just recently taken a YDNA 67 test with FamilyTreeDNA and have only matched with one person at 30 of 35 markers. His name it Ralph F. Bennett. He has (2) female cousins that got him to take the test. They are decended from a James Ellis Bennett. James died in Oregon from drowning while fishing in 1867. He came from Illinois on the Oregon Trail supposedly in the late 40's or early 50's. He was born in Indiana in 1834 I believe. I thought he might be one of the sons of my Andrew Bennett (GG Grandfather). However, I am not sure but he is definately related. Andrew Bennett also had a daughter Minvera Bennett who married an Almon Payne. They went west on the Orego Trail in 1852 from Hancock County, Illinois. I haven't come across a Thomas Bennett in my family line but my Andrew's Family came to western Illinois in 1846 the same time period as your Thomas Bennett came to Iowa. I have no knowledge of Andrew's brothers or sisters so he may have had family that came with him and continued west. Hancock County, Illinois borders Iowa on the Mississippi River. Just thought I would pass on this information, I don't know that any of it really fits with yours. Good luck in your search.
Cedar Rapids, Iowadale3cr@mchs.com