(There may or may not be some faint familial connection for myself and my family about this btw, so please do keep this in mind)
On-and-off search for some info my own needs, I stumbled upon some info regarding a familial line that references purported samurai lineage, and I noticed that there are references to a Sugi namesake, so with some Google-fu, I landed on some info about it being a offshoot of the Sasaki clan. Thing is, all I have on it is a Wikipedia article and nothing more.
Oh and Yoshida Shion, which according to the Wikipedia article claims its of samurai lineage. I find this suspect.
I'm really curious as to the background behind the Sasaki, Sugi, and Yoshida lineages, and if true, that means there must be a mon for the Sugi and Yoshida, of which I havent found and would like to know, just for knowledge's sake, and not of course because of some mistaken link to the samurai, though one can wish...
Do you know the Japanese characters? Just knowing whether it's 佐々木 or 笹木 will help.
There are many different Yoshidas. Do you have any idea where your family might be from originally? There's a very ancient Yoshida clan, as well as other samurai of the Yoshida name from places such as Kai with the Takeda clan and Tosa in Shikoku with the Chosokabe clan.