Perfect Rhymes:
* Cheer (as in "cheer up, little deer!")
* Clear (as in "a clear forest path")
* Near (as in "a deer came near the cabin")
* Sere (meaning dry or withered, as in "the sere leaves of autumn")
Near Rhymes:
* Fear (as in "the deer felt fear from the predator")
* Here (as in "the deer stood here in the meadow")
Other Options:
* Brier (a thorny plant)
* Pier (a structure extending into water - not strictly nature, but could be used in a poetic context)
Let me know if you'd like more examples or a specific kind of rhyme!