mitch-
Culms that are 1.5" to 2.5" in diameter that grow in your area might be somewhat hard to find. I'm not saying it's impossible, but those larger diameters are usually associated with mature stands of bamboo species that do well in more temperate climates than yours. In addition, depending on what the project is, you might want bamboo that has been dried, rather than fresh culms. If you absolutely need such larger-sized culms, you may have better luck just buying directly from one of the online companies that sell and ship various sizes of bamboo culms.

If by "Shiroshima" you mean Hibanobambusa tranquillans 'Shiroshima', it's not. 'Shiroshima' has large variegated leaves and doesn't get nearly as tall as bissetii. Common names for bamboo are not very precise, so maybe there's another bamboo whose common name is "Shiroshima".

Is there anything notable about the culms? Do they have stripes? Do you have photos of the shoots when they're 6" tall or so?