I have been searching desperately for seamless USGS 7.5 minute quads. I am aware that there is a layer available (USA Topo) to ArcGIS users via the online server. However, the quality is just not as good as I would like.
I would have suggested the USA Topo map from ArcGIS Online but I am not sure what kind of quality you are looking for. I feel like that may be your best bet, unfortunately.
I did come across this map view interactive map from the USGS but I am not sure if it is more useful or not:
Viewer | topoView
I will be curious to see if others have a good solution for this.
Are you looking for a specific area? At my last job we manually downloaded them all for LA County and published them to our own ArcGIS Server.
You can get a shapefile of quads here. United States, USGS Quad Grids - Nationwide - Free GIS Data - GIS Data Depot
This site list California ones individually Free California Topo Maps
It has instructions to get the seamless images.
I think you can also get them in bulk by county here Geoportal
I'm not familiar with resources for other states, sorry.
Thank you for all of the comments and suggestions. I ended up downloading the USGS quadrangles that I need from Topoview and then used the agency's grid to clip off the collars around the margins.
Now that you have them clipped you could Create Mosaic Dataset—Help | ArcGIS for Desktop
For many years there was a seamless topo quad collection for all of California at the California Spatial Information Library (CASIL) at gis.ca.gov. However, CASIL has been replaced in recent years by the California State Geoportal. You may be able to locate it on the Geoportal (though I was not able to quickly find it).
Chris Donohue, GISP
Also, there used to be the easy-to-remember site seamless.usgs.gov, but that site is also gone. Now it leads to the USGS National Map site, which likely has it, but one will have to dig a bit.
The National Map
Retrieving data ...