An curved arrow pointing right. From a pile of seaweed to a packet of soy sauce. The London startup Notpla has created a plastic alternative from seaweed that's biodegradable — and even edible.

Generally, edibles come in 100 milligrams of cannabinoid per packet, and each serving is about 5 milligrams. Consider starting with 2.5. Now, there are also fast-acting edibles, which take effect ...