The search was launched after the discovery last week of mustard gas canisters, and the subsequent arrest of three people who have been released on police bail.
There are no details of what the boxes contain but police say the search of the woods is on-going.
Police have also confirmed that work continues at a lake in Stixwould.
That particular search also involves the Royal Navy Bomb Disposal Dive Team, Army Bomb Disposal, Lincolnshire Fire & Rescue, EMAS and the Environment Agency.
There have been unconfirmed reports that items found in the lake have been sent for detailed examination.
With regard to the search of the lake, Supt Phil Vickers from Lincolnshire Police said: “I am satisfied with the progress being made so far.
“Protecting the public and responders on scene remains our priority, so all agencies are working in the safest way possible to achieve that.
“We are also at Roughton Moor Wood in Woodhall Spa and can confirm that a total of 11 boxes have been located, with the search ongoing.
“We are working with East Lindsey District Council and Lincolnshire Wildlife Trust to consider whether any restriction on access to the site may be appropriate for the future.
“I’m grateful for the support of all of the agencies involved and positive comments from the local community.
“We will continue to keep everyone updated on progress”.
• A public meeting about the recent discovery will take place on Thursday evening.