No, Hallmark doesn't yet have a card to mark "420." But many other businesses inside and outside the multibillion-dollar cannabis industry are using April 20, or 4/20, to roll out marketing and social media messaging aimed at connecting with consumers driving the booming market.

On Saturday, Lyft is offering a $4.20 credit on a single ride in Colorado and in select cities in the U.S. and Canada. Carl's Jr. is using a Denver restaurant to market a hamburger infused with CBD, a non-intoxicating molecule found in cannabis that many believe is beneficial to their health.

On 420 last year, Totino's, a maker of frozen pizza snacks, tweeted an image of a microwave and an oven with the message: "To be blunt, pizza rolls are better when baked."