Obligatory mention of the "18th Century Cooking" YouTube channel: https://www.youtube.com/channel/UCxr2d4As312LulcajAkKJYw

The Mushroom Ketchup recipe is one I repeatedly go back to -- it's just that good: https://www.youtube.com/watch?v=29u_FejNuks

I also encourage anyone who still has their elderly relatives with them to ask them for recipes they had from their era. My family keeps a common cookbook, and it's nice to be able to pull out Grandma's shrimp-dip recipe for special occasions.