Liquid or dry yeast??? If liquid, and it hasnt' been refrigerated, then forget. Personally I'd be far more worried about the LME than anything. Based on your yeast, I'd guess the kits are at least a year old or more. LME will develop the extract twang after it sits awhile. It's not the worst taste in the world, but it's not something I like. Keep the bags, caps, etc... and toss the ingredients in my opinion.
Or you could say what the hell, it's free and as long as you've got the open fermenting room, brew up a batch and see what you get.