Well then, what was a family emblem of Matabei Mototsugu Goto?
An ancestor of Matabei Goto was Kamatari Fujiwara. So I can imagine that would be "Fuji" (wisteria).
A result of my research of family emblems of Goto families in Japan is shown below:
As "Sagari-Fuji" has a tendancy to be avoided in a sense of decreasing fortune, it is replaced with "Agari-Fuji", which is increased in usage.
"Sagari-Fuji" appears on a box containing a family-tree which was inherited by a direct family line of decendent of the Goto family residing in the Banshu clan (now, in Hyogo Prefecture).
Therefore the family emblem of Matabei Goto might be "Sagari-Fuji".
Actually the Goto family residing at Nishiki, Himeji City, has the family emblem of "Sagari-Fuji", but the family emblem of the Goto family residing at Ohmura, Kasai City, is "Ken-Katabami" (a wood sorrel).
Though different views are aired on this point, please allow me to use "Tachibana" as family emblem of the Goto family, because this is my homepage.

"Sagari-Fuji"