I love sneaking herbs in popsicles! I usually will make a base strong infusion using herbs that are the most suitable for the moment and go from there. Fresh or dried herbs are fine.
For example, during cold season, I would make a strong infusion of immune building herbs such elderberries and rosehips and supportive herbs like licorice root (mucilagenous, great for inflamed bronchials from too much coughing let's say), hyssop and chamomile. Once the herbs have steeped for a while, sometimes even overnight as long as the herb doesn't become bitter (like lavender), I strain it. Once the infusion has cooled, I would use it as the popsicle base liquid..adding whatever else my son likes.
Usually berries and whatever else you'd want in a nutritious thick smoothy. You can't really go wrong here, as long as it tastes delicious! I usually include nut butter, avocado, yogurt or coconut milk and sometimes kale. It really depends what I have on hand. Put everything in a blender adjusting consistency as you see fit. We prefer more creamy popsicles, they're more fun to eat! But if you prefer a less messy version, you can simply just have the cooled infusion with berries and honey.
I found herbal popsicles with relaxing herbs were a really wonderful way to help my then 2 year old son regulate after a busy day. I would run a bath and give him his popsicle in there. It felt like a treat for him and also helped with bedtime!