Golf sized pencils are available at any Staples. I think I paid about $8.00 for a box of about 150 of them...not for survival purposes obviously. I have also seen smaller packs of 5-10 pencils at dollar stores.
Best place, as others have mentioned is the local golf course or ask around at your work. There are usually more then a few golfers in any decent sized workplace who will spot you a few pencils.
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Earth and sky, woods and fields, lakes and rivers, the mountain and the sea, are excellent schoolmasters, and teach some of us more than we can ever learn from books.
John Lubbock