Thanks, all, for your advice.
Sadly, this topic has been discussed to death in the group. (no pun intended!) The associate pastor is generally present at all meetings, and she saw no issue of store-bought goods.
It's one of those things where it's not like we're told to our faces "No, your food isn't good enough." It's more like "Oh, gee, we just didn't have room for your contribution!" I think the reason they only want home-baked food is because there's a mentality of "if you just buy it from the store, you really don't care." Which makes no sense to me, because I know people who do buy store bought food because they care too much to subject people to their cooking.
As far as bringing something like fruit, we used to do that sort of thing. The problem was that it got to the point where the group was starting to be expected to provide entire lunches or to serve large meals provided by caterers. Again, going back to the "work" and "doesn't work" thing, it got to the point where it was the same people having to provide or serve these huge meals, and they, understandably, got tired of it. So, it was decided (after a LONG discussion) that we would only provide very light refreshments, and we're very clear as to what they will be. Obviously the family can have a reception hosted by another group (such as if the person belonged to a circle) or hire a caterer who serves, but if they ask us to do the reception, it's supposed to be very low key.
Anyway, thanks again! I'm glad to know I'm not just being petty. In the future, if I cannot attend the service (and thus make sure my food is put out), I will not contribute food. Clearly they have more than enough and do not require my donations.