Mary is a daughter of Aaron (b.IL) and unknown Bell (b.unk).
She was a widow (Oliver P Pooler) at the time of her death.
residence: 1511 Rowland, Kansas City, Kansas
Informant: Ruth Waddell (daughter), 1871 N 25th Street, [KCK]
DC 17787 (Image)

1850/ ?

Her father, Aaron and Nancy married in 1856.
NOT on this Census (would have been 12y):
1860/ Illinois/ Williamson
A A Bell, 30y b.TN, occ: Farmer
Nancy J, 19y b.IL
Mary M, 2y b.IL
Easter J, 9mos b.IL
Lucinda M, 13y b.IL
Rufus R [Springs], 3y b.IL

NOT on this Census (would have been 22y):
1870/ Kansas/ Mitchell
Aaron Bell, 41y b.TN, occ: Farmer
Nancy, 30y b.IL
Mary, 12y b.IL
Esta, 10y b.IL
Margrett, 8y b.IL
Sarah, 6y b.IL
William, 4y b.IL
Martha, 2y b.KS
Rufuss Springs, 14y b.IL

Beloit's first marriage took place 09 December 1870 when Mary Bell, daughter of A A Bell, exchanged wedding vows with O P Pooler.
[9th paragraph]
http://members.nckcn.com/TIC/Beloit/history.htm Image from the Family Bible
[Sorry, this website no longer works]

1880/ ?

I've added this Census for information purposes only.
Mary does not appear here but her half-sister, Mary "Milley" (Bell) Cushion does:
1880/ Kansas/ Decatur
h/ Alexander Bell, 51y b.TN, occ: Farmer
w/ J Nancy Bell, 40y b.IL
d/ Mary M [Milley] Cushing, 22y b.IL, Married
d?/ M Allen Cushing, 18y b.IL
dil?/ Elizabeth W Cushing, 3y? b.KS
s/ William Cushing, 14y b.IL
d/ Francis Cushing, 9y b.KS
s?/ Lieu Belle Cushing, 6y b.KS
s/ Robert Cushing, 4y b.KS
s/ John B Cushing, 7mos (Nov) b.KS
boarder/ Robert Springs, 23y b.IL, occ: Farmer
[double checked, all information here is correct]

She appears on the 1900 and 1910 Censuses with her husband, Oliver.

1920/ Kansas/ Wyandotte
h/ Mary Pooler, 71y b.IL, Wd, no occ
residence: 1511 Rowland Avenue, KCK

Many THANKS to Barb Phillips
for all the background information and link to Beloit history [which no longer works].