Practical sources of entropy on an Android device? What Android API's can be used a practical sources of entropy ?

Given the requirement of sourcing entropy on the phone for purposes of seeding a PRNG, what are good options ?

Edit:

I have a hard external requirement to periodically supplement the entropy of the RNG, which in the case of SecureRandom, I will do by calling setSeed and passing in the new entropy.

The Android docs for setSeed state:  The given seed supplements, rather than replaces, the existing seed. Thus, repeated calls are guaranteed never to reduce randomness..

As a result, I'm pretty confident that this is the safe and correct way to supplement the entropy of the RNG, but I need guidance as to appropriate on-device sources of entropy.

I have a FIPS compliant HSM on the server side that will contribute, but I need a safe source of additional entropy on the mobile device side.

Recommended options include the lower-order bits of random chunks of memory and phone sensors, and I would appreciate comment in this regard.
Just use SecureRandom and let the OS take care of it.