Going to McDonalds as a kid was 50% about the food and 50% about the toy that you got in your Happy Meal.
Any chance you have any lying around somewhere? They could be worth a few bob to you.
According to LoveAntiques.com, the mini Potato Heads Kids from 1987 could get you $120 (€102.20). Remember those Beanie Babies from 2000? Those are getting $400 (€340.67)
Don't get too excited, as not all toys from back in the day are worth that much.
Most listings for the toys are on eBay, so check it out before heading to Penneys and spending it before you have it.