The stamp is from CTMH's "Whoo's Your Valentine" promotion from last year.
For the heart in the middle, I used the reverse of the floral paper-- it has little hearts all over it. To make it dimensional, I cut four of them, folded them in half and glued the backs together.
Here's the sketch (I took a few liberties with it!):
Hope your Sunday is a fun-day! :)