What type of blue construction foam are you referring to? What type of store would I find it?
ORIGINAL: nctaxi
Shooter, here's the easiest way I know of. Find a piece of blue construction foam, slightly bigger than your plaque. Use the blue foam, it won't fall apart. SHape it to fit your plaque and shape it how you want it. Mix Elmer's and dirt to a peanut butter consistency, spread over faom. While it's drying sprinkle dirt over it. Go to Michael's or Ben Franklins or another hobby shop, buy whatever plants you want . Viola! Simple - fast