|What medium could you use to put flower seeds in and shape it into a heart to be used as a gift for wedding quests?|
|You might be able to sprinkle seeds onto home made paper (while it is still in the wet stage) that is subsequently dried normally and then cut into a heart shape. Guests could then "plant" the paper and the seeds along with it. I would suggest you experiment with this and see if the result is acceptable.
A thicker medium could potentially cause the seeds to become overly damp and begin to germinate, then they would rot before the "dough" dries.