If you want "tea" then that would be a plant that produces tea leaves. Chamomile, maybe? Rose hips, great source of vitamin C.
You might want to browse through an herbal "tea" store or website for some ideas. Check out this, scroll down for a list of "teas" that can be made from common garden plants. Herbal tea - Wikipedia, the free encyclopedia
there is also a section about medical concerns. Some of these plants can be dangerous.
I adore tea. I never drink coffee. Classic tea is the leaf and bud of the camellia sinensis. I've known this forever but never grown a camellia myself. However, our "new" house - a cottage by the sea,has a wonderful garden (that's why I was insistant that we buy the place) and there is a camellia growing in the backyard. I am tempted to pick and dry the buds and leaves and make tea.
Only thing that is holding me back is that maybe it is not 'sinensis" but something that will poison me:))) -- Any horticulturalists out there??
Maybe I should stick to my favourite brand which is Dilmah. Not in the advertising business, just that they produce the best teas one can buy. Hand picked. Beautiful, pure, classic teas.
On the herbal side of things, don't buy tea bags - they are really gross; make your own from fresh or dried herbs. Add honey if you wish and savor the aroma before you imbibe.