Texture Processor
Texture Processor Website
One I did a few years ago is below which is seamless and it looks like stamps to me.

Quote from: Paurex Website
Texture Processor is the unique program for creating various textures. The basic algorithm placed into the heart of Texture Processor allows to get practically unlimited quantity of complex textures in a minimal amount of time. Texture Processor is intended both for 3d-artists and web-designers. Besides, any other users not able to draw in various graphic editors, will receive full pleasure and breadth of actions, working with Texture Processor.
Texture Processor Website
One I did a few years ago is below which is seamless and it looks like stamps to me.











- carpe noctem




)...
features this seems to be worth a try (30€ for private use, 65€ for commercial use, and there's a feature-limited freeware, too).