The pattern is Roses from Queen of Hearts by Louisa Harding. You do have to follow a chart to do the heart design, but it's only a small one (16 stitches). Normally I would run a mile from charted instructions with symbols telling you what to knit, but I wanted to knit this pattern so I gave it a go, and it wasn't nearly as painful as I thought it would be.
Any dk yarn could be used for the pattern.
It has become a yearly tradition in our house for me to bake Mr. Knot Garden a heart shaped cake for Valentine's Day. (In return he supplies me with chocolate.) This year it's a Raspberry Valentine's Cake with cream cheese frosting, from Gorgeous Cakes by Annie Bell, a fantastic book with very reliable recipes. I had this book for Christmas and I've been working my way through it.