Are there any sites telling you who produces Store brand items, such as “Sam’s Choice” etc.?
I know that the answer to “who produces the store brand” is often complicated by the fact that stores often source the same product from several different manufacturers–depending on price, availability, etc. So the store brand ketchup may be made by Heinz one year and “Bob’s Cheapo Condiments” the next.
Also, many manufacturers and stores try pretty hard to keep the info a secret.