You're either unlucky, or in a highly populated area (such as Boston). Area's that see few people, or people with built up homesteads, tend to have plenty of leaves from what I have seen.
There's also this list:
http://salemwiki.info/index.php/Cloak_%26_DaggerTumbleweed's (550 C&D) are fairly common in Plains biomes. Earthworm Python's (750 C&D) are also kind of common if you are checking all of the Stumps. Stumps also (rarely), have the Whispering Snake Skull's in them (5,000 C&D). The Singing Old Log's (900 C&D) are all over the place in Forest biomes, spawning both on the ground and, again, in Stumps.
Honestly though, I'd ignore the tumbleweeds and maple leaves and just find yourself a forest (the green and brown type on the minimap, not the puke-orange and yellow types that have maple leaves), and hunt Singing Old Logs. These also have high Law & Lore (1900) plus Sparks & Embers (2600?), which you'll also need for combat related skills.