This source: Jordan Dodd, Liahona Research. Ohio, Marriages, 1803-1900 [database on-line]. Provo, UT, USA: Ancestry.com Operations Inc, 2001, shows the record of the marriage of Alexander Wilkinson and Mary Ann Cannon on 11 Dec 1846 in Belmont, Ohio. Note it shows 1846, not the 1830s as you said.
There's a James Cannon in Smith, Belmont, Ohio and a John N. Cannon in Flushing, Belmont, Ohio on the 1840 U.S. federal census. Looking at those, they each have daughters (age 10-14 on the census) that could be your Mary Ann.
I located what appears to be Alexander & Mary on both the 1850 & 1860 U.S. federal census. In 1850, Mary shows as age 20 & born in Ohio. They have a son Seth, age 3. (Ref: Year: 1850; Census Place: Smith, Belmont, Ohio; Roll: M432_661; Page: 251B; Image: 811) Is this them? In 1860, they're still in Belmont, OH & Mary shows as age 30 born in OH.
Since Alexander & Mary lived in Smith, Ohio, I'd look first at the James Cannon that was in Smith on the 1840 census.