Mom's Organic Market Starts Fighting Plastic

Earlier this month -- while Comcast was keeping me off the Web and phone -- Mom's Organic Market announced a plan to ban bottled water and re-make operations to cut down on plastics.

First, they stopped selling water in plastic bottles.  They're installing filtering machines so you can use reusable containers for water -- including the first gallon for free.  They're also eliminating some vegetable bags, plastic bags in the bulk section, and getting biodegradable bags, wax paper and more.

Of course, the best recycling that you can do at Mom's in Jessup is pick up organic vegetables to toss in your compost heap.

My real question is about these "biodegradable" plastics like the clamshells Mom's (formerly My Organic Market) will use for salads.  Can you just throw those in a compost pile?  How can I tell which plastic-looking items are compostable?