> put some tomato slices on them, but I can't figure out how to keep them.
>
> If I buy a big one, I do not use it fast enough to use \

Brian, have you tried buying just small amounts of fresh things like
celery, tomatoes, green pepper, etc., at a neighborhood supermarket
deli counter? Ours has a salad bar - that's where I go for celery,
particularly, since I never use up a whole stalk.

N.