I would forage for herbs. In fact, i would love to. But i live in a city. This is unfortunate because i prefer nature, but i cant afford anywhere deep in nature.
Unfortunately where I live few things I could forage, but I can think of a park where I could find these, any pine tree incense recipee?
Don't underestimate what grows in cities. Only because something is not rare, doesn't mean it isn't powerful. Dandelions are the first that come to mind: I can't think of anything that embodies nature's resilience as well as dandelions. Those little yellow fuckers (and I say this with love) will grow everywhere, even in cities. As long as you're not planning on consuming them, get at it! (If you plan on eating/drinking them, pick them in nature and not in the city). You can even help them spread in the city (as if they needed it, right?) by getting their mature flowers and spreading them in the cracks in the concrete. I've seen calendula grow wild in the city where I live, as well as wild oregano, st john's wort and nettles, only to name a few.
Speaking of nettles, I've been growing them indoors as decorative plants, collecting their leaves and drying them, planning on using them for some ritual in the future. They're connected to Mars. You can probably grow more plants, and while it does take some extra effort, and it's not exactly foraging, you can see it as an extra: you can imbue them with your intent from seed to harvest, and make sure you harvest them in the right astrological day and hour.
As of foraging, I use fatwood as an incense (one thing I won't support my local metaphysical shop for is selling overpriced palo santo when I can just go to the local woods and find as much fatwood as I'll ever need). Other stuff I forage are Rhododendron tomentosum (marsh rosemary), nettles, thistles, pine resin and all sorts of pebbles, stones, pinecones and cool sticks.