The 1880 census for Madison Co., AR which was taken June 1, 1879-May 30, 1880 lists William and Penelope in Household #150 in Lamar Township. The information is as follows:
William Lindley, male, 45, married, farmer, MO, MO, MO.
Penelope Lindley, female, 42, married, wife, keeping house, AR, TN, TN.
Daniel Lindley, male, 15, son, farm laborer, AR, MO, AR.
Eddie Lindley, male, 12, son, farm laberor, AR, MO, AR.
Margaret Lindley, female, 10, daughter, AR, MO, AR.
James Lindley, male, 6, son, AR, MO, AR.
According to my notes the Dec. 1955 issue of "Flashback" Page #20 says that Penelope Hinson married William Lindley on Nov. 25, 1858 by Rev. Z.M. Vaughan. Further research lead me to believe Rev. Vaughan was Penelope's uncle.
I did not note the date of the 1870 census (I always seem to forget something) but the information that I have on the William Lindley family is the same as yours. Strange that Daniel is not mentioned in this census as he would have been about 5 at the time.