Buy Local. Buy FSC.
The lumber industry has invented some confusing certification programs. They are all basically green washing.
The best option for off the shelf lumberis FSC. Forest Stewardship Council certified wood. Any product that is FSC certified should have the FSC stamp on the product. If it does not do not trust that the wood is sustainably harvested. It may be but there is no guarantee. Although many in the industry are opposed to this program, No viable alternative has been proposed that can guarantee to the consumer that the forest is truly sustainably managed.
Avoid the forest industry greenwash label of SFI.(notice the "accidental" similarity to FSC!) It sets the bar of sustainability way too low.
Also locally owned and operated mills can be a good option. But you must establish a relationship with the owner/operators. Local does not equal sustainable. Although family owned companies sometimes have an incentive to steward the land for their future generations for their family much more so then corporateowned lumber companies.
Plywood
Mead Clark Lumber (see website for up to date stock lists URL in company list section)
Siding
Mead Clark Lumber (see website for up to date stock lists URL in company list section)
Interior Trim including, base, case, and crown.
stocked locally at Home Depot
Caution: The representatives at the pro desk have often said to me that all Home Depots wood stock is FSC certified. But that is not the case, only items that have the FSC stamp on the product itself are FSC certified.
Prefabricated Wood Products
FSC Trusses
Mead Clark Lumber (see website for up to date stock lists URL in company list section)
FSC Gluelam Beams
Mead Clark Lumber (see website for up to date stock lists URL in company list section)