We use Pillsbury tube breads, Ener-G brand breads, and Fiber One. Van's has a GF frozen french toast that we've used. Last time I checked none of those were on shared lines with peanuts or tree nuts.
Fiber One is owned by General Mills but the breads are baked and distributed by different local bakeries under license to GM. Today I decided to call the bakery in my area (Gold Medal Bakery in Fall River, MA -and thank you, Jessica, for pointing out that bakery is not owned by GM
) They said their Fiber One breads are not on shared lines with peanuts or treenuts.
However, some of the Fiber One breads do contain sesame and other seeds (and are on run on the same lines.) They are NOT good at labeling for sesame. Sometimes it is in the Contains statement at the end, and sometimes it is in the ingredients list. And I've never seen a "May Contains" for sesame even though the bakery just told me they do share lines.
I can see why people make their own bread!