Essential Picnic Checklist template

For Toting and Seating:  

Picnic basket or canvas bag 

Cooler

Picnic blanket (preferably waterproof on the bottom)

Picnic chairs (if anyone in your group is not happy on the ground) 

Portable picnic table (if that's the kind of picnic you're having!) 

For Serving:

Plates

Utensils (including serving utensils)

Napkins

Cups 

Drinks (including lots of water)

Bottle opener

Cutting board (also useful as a level serving surface, perfect for drinks) 

Sharp knife (even if you don't plan to cut things, it's still a good idea) 

Salt and pepper

Mustard, mayo, ketchup, etc., if needed (a great way to make use of extra packets from a takeout place) 

For Cleanup:

Paper towels (and maybe wet wipes)

A couple of dishtowels (always handy, and useful to buffer and support dishes in transport) 

Extra plastic containers or sturdy zipper-top bags for packing up dirty utensils, leftovers, etc. 

Trash bags

Other Essentials:

Sunscreen

Hats

Insect repellent

Flashlight (if you plan to be out into the evening hours) 

Sport or activity equipment (Frisbees, balls, bubbles, water guns ... whatever the crowd likes) 