Hi Leslie, One food that we had in our garden last year was fresh strawberries that we bought at Kroger. They were washed the night before. We had lots of compliments on them. I tried to offer more non sweet items but did have a few sweets. We bought in bulk the small individual packages with an assortment of cookies, cheese bits, etc. that the garden visitors could carry with them as they walked the garden or could eat on the bus. We did have an assortment of sodas along with cold bottled water but bought the small cans. Don't remember the # of ounces, but they are cheaper and less waste. I do not recommend that you try to cook lots of something in advance. You will very quickly overwhelm yourself trying to have enough for 600 visitors. KEEP IT SIMPLE!
Doris