There are plenty of wild teas you can forage and make out on your travels. Pine needle tea is always the one that our mentors always recommend because it is available year round, especially in arctic winter scenarios.
However, in our warmer, maritime climate, there are plenty of plants that make an exceptional tea.
My current favourites (seasonal), are Meadowsweet flowers and Russian chai (Rosebay Willow herb leaves, lightly fermented and dried). But fruit plant leaves (raspberry, blackcurrent etc) work well and are much tastier than the insipid and expensive fruit teas you can buy.
We only drink wild, foraged teas these days and every month brings a new flavor.
But do your research and, as has already been said, only drink in moderation. Gen up on your plant ID and be sure before you consume (there is a huge bank of knowledge on here).