Water reclaimed wood?

I haven't come across use of a product like this before but It seems like it would technically still be a 'virgin' resource and so wouldn't qualify for MRc3 and the wood would need to be counted toward Certified Wood.

Others have a different experience?

In the case of logs salvaged from old logging operations (from decades ago), these are often marketed as "reclaimed," which makes me think they have and can be applied under this credit.I haven't seen a product from a recent flooding but I think there's a case for it—essentially it's a discarded resource that's being saved and put to useful purposes, and displacing demand for virgin timber.Not an airtight case, so worth checking with GBCI or not counting on it in your calcs.

The Reference Guide defines salvaged or reused materials as “construction materials recovered from existing buildings or construction sites and reused.” Your trees do not appear to meet this definition.

Even though this wood comes from an unconventional source, I believe that you would be required to include its costs when evaluating MRc7 Certified Wood. LI#2225 (http://www.usgbc.org/leed-interpretations?keys=2225) seems to support this conclusion, so does LI#2449, a similar LEED for Homes interpretation (http://www.usgbc.org/leed-interpretations?keys=2449).

However, as Tristan suggests, it might be wise to seek clarification from GBCI.