I have some left over mmf I kept in my pantry in a ziploc bag from last weekend.
Does it go bad or can I use it for flowers and accents?
Can people still eat it if it has'nt been refridgerated for storage?

Absolutely. Just wrap it tightly in plastic wrap and then in the ziplock bag. If it is going to be a while before you use it, just freeze it. It thaws pretty quickly.