Thought maybe a dio person may know a source...

Depends on what you're looking for for a blanket.....a plain one color would be most easily replicated using the tissue paper and glue for tarps maybe?  If you're looking for the stereotypical red and white plaid or checkered picnic cloth though, I don't have any ideas other than real fabric.  Plates and stuff could probably be found in sme sort of military field kitchen set, or you sould maybe find some doll plates?  Something like a small dollhouse saucer plate would be a large dinner plate in 1/35 maybe.  Just some thoughts.

Try these folks, they have a bunch of military and civilian dio. accessories. 

http://www.milminwh.com/

 As for the blanket, try a dollhouse site that offers downloadable wallpaper and you might find something that would pass for a blanket....little white glue and water on it and there you go!

razorboy

What Bodge said.  Check Verlinden's products.  I know that you can get bottles, and other food related items.  I even recall something like a set of kitchware and utensils.