There can be discounts offered on room only reservations (where by you do not get tickets to the actual attractions, but can do so for the hotels) for seniors, however these are subject to availability, so can be very difficult to acquire, especially at peak tourism times in the year.
A valid ID showing your official age is required at check-in in order to qualify for this discount. If you cannot provide this, then the discount will be null.
Another option is that of discount coupons, which are not always so readily available. Again, these are subject to availability and proof of ID is required at the time of purchasing the coupons.
Although Disneyland does not offer senior price tickets, there are ways in which "senior” status can be used in order to receive other discounts whilst visiting Disneyland.
Find out how long you want to visit Disneyland for. Certain times of the year are less busy than others, therefore various discounts are available during the least busy times as the park try to entice more customers during these low throughput periods.
Book reservations early, last minute options are often far more expensive. Again, find out about the cheaper times of the year and book a few months in advance to achieve the maximum benefit.
Have a look at package deals for the resort. Booking multiple tickets at the same time, tickets for multiple days at once, or hotel and park combined ticket packages can give discounted prices.
In short, there are not really any officially offered senior citizen priced tickets, but there are a few ways in which you can potentially receive a discount if you are not interested in the attractions, or willing to go during off-peak times and enquire about getting a deal.