I have an old metal lunch box with the Partridge Family when the children were real young. Do you think it may be worth anything? It also has the thermos in it.

Check eBay sales prices on it. My guess is that if it's an original, it's worth more than you think.

If it is in good condition try seeling it on E Bay. You can probibly get about $25 or more for it.
Good Luck
Bryan