Thank you for your question, Deepti.  Here is a list of plants that grow in nature under sequoias:  

"Common understory species include Pteridium aquilinum var. lanuginosum [eagle fern], Polystichum munitum [Western swordfern], Gaultheria shallon [salal], and Ceanothus velutinus [snowbrush ceanothus, red root and tobacco brush]. Where it has been introduced in Russia, Sequoia has been reported to hybridize with Japanese cryptomeria (Cryptomeria japonica)."  Plant Data Sheet (washington.edu)  So, just check out the forests in which it grows, and you can find these.  Good luck!