If you'd like to have a picnic lunch and don't like sandwiches you can always put your salad in a drinking glass and cover it with bandana or cloth napkin and a rubber band.
The tip comes from dessert weblog Tartelette who features a Salmon & Quinoa Salad in the glass in the above photo. See the source link below for the recipe.
This idea is one of those that will seem like common sense to some and a revelation to others. You could just use Tupperware, but using the drinking glass and the bandana makes it more aesthetically pleasing which is half the idea of a picnic to begin with.